I’m closing this thread on the grounds that it’s not specific enough for us to solve.
It looks like even after chasing an initial hypothesis that this might be related to a change in the OAuth behavior regarding refresh tokens, we didn’t get enough context to be able to reproduce the problem, let alone solve the problem. If you see this error and need more help, we would need more details, like which endpoints you are calling, which OAuth flow you’ve tried, and steps to reproduce.