Yeah, debugging with @mcondarelli has showed that OpenWRT does actively rename interfaces both on startup and shutdown, so that’s definitely a bit of a problem.
Ubuntu or Debian usually do not do that, so those are a bit weirder.
Do you have the incusd.log errors you get when shutting down an Ubuntu or Debian container?
I wonder what device has gone missing in this case. Also the incus config show --expanded NAME for that instance just prior to the incus stop would be helpful.