Yes, I reported the bug in horizon, but fixed it in nova, sorry for the confusion caused, this is the only patch at:
https://review.opendev.org/c/openstack/nova/+/906813

there's nothing else, and the horizon patch I will abandon it.

====================================

Here is the test

Before the patch:

1.Booting an instance from volume, minimum memory is 8G, all the detail as follow:
()[root@busybox-openstack-67c45bbfc8-qt8fh /]# nova show bc2dbab9-eb2f-4a4f-b16a-e7392b5af4cb
+--------------------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Property                             | Value                                                                                                                                                                                                                        |
+--------------------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| OS-DCF:diskConfig                    | MANUAL                                                                                                                                                                                                                       |
| OS-EXT-AZ:availability_zone          | test                                                                                                                                                                                                                         |
| OS-EXT-SRV-ATTR:host                 | node-5.domain.tld                                                                                                                                                                                                            |
| OS-EXT-SRV-ATTR:hostname             | zztest                                                                                                                                                                                                                       |
| OS-EXT-SRV-ATTR:hypervisor_hostname  | node-5.domain.tld                                                                                                                                                                                                            |
| OS-EXT-SRV-ATTR:instance_name        | instance-00000350                                                                                                                                                                                                            |
| OS-EXT-SRV-ATTR:kernel_id            |                                                                                                                                                                                                                              |
| OS-EXT-SRV-ATTR:launch_index         | 0                                                                                                                                                                                                                            |
| OS-EXT-SRV-ATTR:ramdisk_id           |                                                                                                                                                                                                                              |
| OS-EXT-SRV-ATTR:reservation_id       | r-0lkf8c4q                                                                                                                                                                                                                   |
| OS-EXT-SRV-ATTR:root_device_name     | /dev/vda                                                                                                                                                                                                                     |
| OS-EXT-SRV-ATTR:user_data            | Q29udGVudC1UeXBlOiB0ZXh0L3BsYWluOyBjaGFyc2V0PSJ1cy1hc2NpaSIKTUlNRS1WZXJzaW9uOiAxLjAKQ29udGVudC1UcmFuc2Zlci1FbmNvZGluZzogN2JpdAoKI2Nsb3VkLWNvbmZpZwpjaHBhc3N3ZDoKICBsaXN0OiB8CiAgICByb290OjAwMDAwMHpaCiAgZXhwaXJlOiBmYWxzZQ== |
| OS-EXT-STS:power_state               | 1                                                                                                                                                                                                                            |
| OS-EXT-STS:task_state                | -                                                                                                                                                                                                                            |
| OS-EXT-STS:vm_state                  | active                                                                                                                                                                                                                       |
| OS-SRV-USG:launched_at               | 2024-01-29T11:18:36.000000                                                                                                                                                                                                   |
| OS-SRV-USG:terminated_at             | -                                                                                                                                                                                                                            |
| accessIPv4                           |                                                                                                                                                                                                                              |
| accessIPv6                           |                                                                                                                                                                                                                              |
| addresses_labels_mac                 | ["fa:16:3e:f1:92:f3"]                                                                                                                                                                                                        |
| config_drive                         |                                                                                                                                                                                                                              |
| created                              | 2024-01-29T11:14:01Z                                                                                                                                                                                                         |
| deleted                              |                                                                                                                                                                                                                              |
| description                          | -                                                                                                                                                                                                                            |
| estimated_deleted                    |                                                                                                                                                                                                                              |
| flavor                               | 2C-8G (9)                                                                                                                                                                                                                    |
| hostId                               | 34b64c722400ed576b67e4ae501983825ae318af1ac63a07951013c7                                                                                                                                                                     |
| host_status                          | UP                                                                                                                                                                                                                           |
| id                                   | bc2dbab9-eb2f-4a4f-b16a-e7392b5af4cb                                                                                                                                                                                         |
| image                                | Attempt to boot from volume - no image supplied                                                                                                                                                                              |
| key_name                             | -                                                                                                                                                                                                                            |
| locked                               | False                                                                                                                                                                                                                        |
| metadata                             | {}                                                                                                                                                                                                                           |
| name                                 | zztest                                                                                                                                                                                                                       |
| os-extended-volumes:volumes_attached | [{"id": "070dbe50-4b07-4dfb-aba7-84ca26056ec3", "delete_on_termination": false}]                                                                                                                                             |
| progress                             | 0                                                                                                                                                                                                                            |
| security_groups                      | default                                                                                                                                                                                                                      |
| share_net network                    | 192.168.111.164                                                                                                                                                                                                              |
| status                               | ACTIVE                                                                                                                                                                                                                       |
| tags                                 | []                                                                                                                                                                                                                           |
| tenant_id                            | 3b719b26cb354213bdcad345c642b56a                                                                                                                                                                                             |
| trusted_image_certificates           | -                                                                                                                                                                                                                            |
| updated                              | 2024-01-29T11:20:20Z                                                                                                                                                                                                         |
| user_id                              | 7ef32ffeda9d4302987ed3c66274cccb                                                                                                                                                                                             |
+--------------------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

2.resize to memory 1G flavor 2, resizing is successful, but it may cause the instance running failed by insufficient memory.
()[root@busybox-openstack-67c45bbfc8-qt8fh /]# nova flavor-show 2
+----------------------------+-------+
| Property                   | Value |
+----------------------------+-------+
| OS-FLV-DISABLED:disabled   | False |
| OS-FLV-EXT-DATA:ephemeral  | 0     |
| description                | -     |
| disk                       | 0     |
| extra_specs                | {}    |
| id                         | 2     |
| name                       | 1C-1G |
| os-flavor-access:is_public | True  |
| ram                        | 1024  |
| rxtx_factor                | 1.0   |
| swap                       |       |
| vcpus                      | 1     |
+----------------------------+-------+

()[root@busybox-openstack-67c45bbfc8-qt8fh /]# nova show bc2dbab9-eb2f-4a4f-b16a-e7392b5af4cb | grep flavor
| flavor                               | 1C-1G (2)                                                                                                                                                                                                                    |

After the patch:

1.I tested it in wallaby, resize again then raise the error
()[root@busybox-openstack-67c45bbfc8-qt8fh /]# nova resize bc2dbab9-eb2f-4a4f-b16a-e7392b5af4cb 2
ERROR (BadRequest): Flavor's memory is too small for requested image. (HTTP 400) (Request-ID: req-8d49b684-11c4-4a6e-8f1b-05f4d0318432)

()[root@busybox-openstack-67c45bbfc8-qt8fh /]# nova show bc2dbab9-eb2f-4a4f-b16a-e7392b5af4cb | grep flavor

| flavor                               | 4C-8G (12)                                                                                                                                                                                                                   |