I have verified the fix using systemd 252.5-2ubuntu3.2 in lunar-proposed:

Creating a fresh container:

nr@six:~$ lxc launch ubuntu-daily:lunar lunar
Creating lunar
Starting lunar                                
nr@six:~$ lxc exec lunar bash

In the container, after enabling -proposed:

root@lunar:~# apt update && apt install -y systemd
[...]
root@lunar:~# apt-cache policy systemd
systemd:
  Installed: 252.5-2ubuntu3.2
  Candidate: 252.5-2ubuntu3.2
  Version table:
 *** 252.5-2ubuntu3.2 500
        500 http://archive.ubuntu.com/ubuntu lunar-proposed/main amd64 Packages
        100 /var/lib/dpkg/status
     252.5-2ubuntu3.1 500
        500 http://archive.ubuntu.com/ubuntu lunar-updates/main amd64 Packages
     252.5-2ubuntu3 500
        500 http://archive.ubuntu.com/ubuntu lunar/main amd64 Packages
root@lunar:~# vi /etc/netplan/50-cloud-init.yaml 
root@lunar:~# cat /etc/netplan/50-cloud-init.yaml 
# This file is generated from information provided by the datasource.  Changes
# to it will not persist across an instance reboot.  To disable cloud-init's
# network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
network:
    version: 2
    ethernets:
        eth0:
            dhcp4: true
            optional: true
root@lunar:~# netplan generate
root@lunar:~# netplan apply
Cannot call openvswitch: ovsdb-server.service is not running.
root@lunar:~# time SYSTEMD_LOG_LEVEL=debug /usr/lib/systemd/systemd-networkd-wait-online --timeout=5
Found link 13
Found link 1
eth0: link is ignored
lo: link is ignored

real	0m0.003s
user	0m0.003s
sys	0m0.000s
root@lunar:~# echo $?
0

I also ran the test from bug 1982218 again to ensure that does not regress:

On the host, I have clean-lunar-amd64, and detached it's default network interface:

nr@six:~$ virsh detach-interface clean-lunar-amd64 network
Interface detached successfully

Then, in the VM, configure systemd-networkd to use DHCP on all en* interfaces:

root@clean-lunar-amd64:/home/nr# apt-cache policy systemd
systemd:
  Installed: 252.5-2ubuntu3.2
  Candidate: 252.5-2ubuntu3.2
  Version table:
 *** 252.5-2ubuntu3.2 500
        500 http://archive.ubuntu.com/ubuntu lunar-proposed/main amd64 Packages
        100 /var/lib/dpkg/status
     252.5-2ubuntu3.1 500
        500 http://archive.ubuntu.com/ubuntu lunar-updates/main amd64 Packages
     252.5-2ubuntu3 500
        500 http://archive.ubuntu.com/ubuntu lunar/main amd64 Packages
root@clean-lunar-amd64:/home/nr# cat > /etc/systemd/network/10-dhcp.network << EOF
[Match]
Name=en*

[Network]
DHCP=yes
EOF
root@clean-lunar-amd64:/home/nr# systemctl restart systemd-networkd

Now, back in the host, I attach a network interface without DHCP:

nr@six:~$ virsh attach-interface clean-lunar-amd64 network no-dhcp
Interface attached successfully

In the VM, check that wait-online times out since the interface does not get configured:

root@clean-lunar-amd64:/home/nr# /lib/systemd/systemd-networkd-wait-online --any --timeout=5
Timeout occurred while waiting for network connectivity.
root@clean-lunar-amd64:/home/nr# networkctl 
IDX LINK TYPE     OPERATIONAL SETUP      
  1 lo   loopback carrier     unmanaged
  3 ens3 ether    degraded    configuring

2 links listed.

From the host, attach another interface that will get DHCP:

nr@six:~$ virsh attach-interface clean-lunar-amd64 network default
Interface attached successfully

And finally, in the VM, run wait-online again and see that it will exit successfully when the second interface is configured:

root@clean-lunar-amd64:/home/nr# /lib/systemd/systemd-networkd-wait-online --any --timeout=0
eth0: Failed to update link state, ignoring: No such file or directory
root@clean-lunar-amd64:/home/nr# networkctl 
IDX LINK TYPE     OPERATIONAL SETUP      
  1 lo   loopback carrier     unmanaged
  3 ens3 ether    degraded    configuring
  4 ens9 ether    routable    configured 

3 links listed.