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...

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@purpleidea clear as crystal!
@dneary Not sure if serious or sarcastic :/
@purpleidea @dneary it’s a joke — crystal meth0 etc. 😏
@skitt @purpleidea Merci Stephen! Désolé James, j'ai pas pu m'en empêcher.
@skitt @dneary doh! My brain was apparently off:p
@purpleidea @skitt Undoubtedly from all the meth, James.