ubuntu images for 18.04 and 20.04 not working on some machines since january 2021

Hi all,

since january I am faceing a problem while commissioning or deploying ubuntu 18 or 20 on some of my machines.
The processes end up in initramfs, I guess it has something to do with BOOTIF and no MAC address is provided.
But on some machines it is working proberly...

And ubuntu 16.04 is working fine for all machines.

If I rollback the locally stored images to the snapshot of december everything works properly:

scp -r /snapshot-20201202-145038/ubuntu/amd64/*20.04* /var/snap/maas/common/maas/boot-resources/current/ubuntu/amd64/

Maybe you find the time to check the change log of the images, if there was any modification related to that.
It could be related to this fixed bug form 2018:
https://bugs.launchpad.net/maas-images/+bug/1749019

Thanks in advance!

Best regards,
Philipp