In my case, it was a combination of bad timing and tax code changes. My codes expired after Sep 1, 2021 when new tax codes went into effect. First, I had to renew my Tax and Banking Agreements, then wait for Apple's ill-timed maintenance to complete for my changes to be accepted. Then, I had to update my banking information because for whatever reason it was cleared. However, the edit button was disabled, so I needed to modify the HTML (Dev tools) to first enable the button. Then I made my changes and submitted. Very stupid.

My customers are suddenly getting this message in production. Some have previously downloaded my app, others are new. The codes are two months old and still active for another month, and I generated new codes set to expire in Dec 2021 (4 months), yet the same message. Anyone figure this out?