After install, the GRUB default is the same as during installation

[Nick Celebic]

I have created an Ubuntu 24.04 template with Packer. Hardly anything has been modified from my 22.04 template creation which works.

Cloudinit install userdata: https://paste.ubuntu.com/p/CmzYX84fDx/

Boot command:
c<wait>linux /casper/vmlinuz --- autoinstall ds=\"nocloud-net;seedfrom=http://{{.HTTPIP}}:{{.HTTPPort}}/u24_cloudinit/\"<enter><wait>initrd /casper/initrd<enter><wait>boot<enter>

In 22.04 and 24.04, the image is created and templated. When provisioning the 22.04 image, /etc/default/grub contains:
GRUB_CMDLINE_LINUX_DEFAULT="quiet"

This is 24.04:
GRUB_CMDLINE_LINUX_DEFAULT=autoinstall ds=nocloud-net;seedfrom=http://192.168.51.84:5555

Somehow, the default is being set as whatever the boot install was set to.