Both on 1909 and recently, on 2004.

I think it happened recently with version 2004 and build 19041.631.

Randomly, but sporadically, on reboot, Windows 10 tells me that that there's a problem with my account and shows a fix button. The most recently, I had to enter my PIN after clicking on the "Fix" button on system-number-one.

Then it will be like nothing happened. Looks like a bug that's related to the bug I faced on 1909.

It appears to be a problem with mainly Windows users using a Microsoft account.

Looks like if you face a message like that and Windows shows the "Fix" button, makes you re-enter your PIN and you re-enter the PIN, then there's probably no further action required.

Marked as solved for now.