ci-runner-01 invalid ubuntu package signatures

Not entirely sure what's happening here, but many of my jobs are getting invalid package signature errors from apt-get.

It seems to be happening on my jobs assigned to ci-runner-01 (such as https://gitlab.torproject.org/jnewsome/sponsor-61-sims/-/jobs/39402), but not to the same jobs when assigned to other runners (such as https://gitlab.torproject.org/jnewsome/sponsor-61-sims/-/jobs/39420)

Maybe it's a problem with one of Ubuntu's package mirrors, and ci-runner-01 consistently gets the bad one?