We have the same problem, but on the Google Play Store.
We have an brand name app used by millions of people. We uploaded an update where the only change was a new Firebase library.
Google rejected the update for vague reasons (“violation of Google Play policies” but not telling us which one).
Appealing the rejection, the CSR just pasted the vague policy thing back at us. We asked for more information and they just closed the ticket.
So we took the exact build that was accepted, incremented the version number, and uploaded that. Rejected again.
And there’s no real human to talk to.
No idea what’s going on at Google.