Wow, more time spent on this than I care to admit, but, it turns out you can't use eth* names on Linux anymore if you actually care about automation! TIL.

Default device names for anything #mgmtconfig manages are now going to be meth0, meth1, methN, unless someone has a better idea.

https://github.com/systemd/systemd/issues/16665#issuecomment-669167184

Failed to rename network interface: File exists · Issue #16665 · systemd/systemd

systemd version the issue has been seen with 245 Used distribution Ubuntu 20.04 Expected behaviour you didn't see Network interfaces should have been renamed according to .link files. Unexpected be...

GitHub
@purpleidea Ironic since meth is what seems to have led to the abomination that is predictable interface naming.