Same with 8.5 2023-05-13 (build 85550474) on our demo setup.
We had once the same problem with our client's DB.
log:
2023-06-07 11:04:09 (1) AD CallHal("EmailValidationStatusWithStdID")
2023-06-07 11:04:09 (1) AD Login Failed 78.60.157.112:56792: ad@stabilios-sistemos.lt