Verify your email -> An unknown error has occurred loop on legacy @mac.com account

I have an old @mac.com apple id and am stuck in endless "Verify your email address -> An unknown error has occurred" loop on appleid.apple.com icloud.com account.apple.com. But I am able to log in through settings on mac and ios. I did have "access iCloud data on the web" off for a while. But I turned it back on a year ago. Maybe that is related?

I tried password resets via iforgot

Signing in and out

Do I need to contact apple for some sort of reset?