I am having the same issue.....but.

I am experiencing the same issue with one of our Xfinity email accounts when using the Samsung Email app.  My email account will not validate/authenticate since 11/6/23 @2:32am.  Everything is fine and works across all of my non Samsung devices.  Every once in awhile the app will give me the opportunity to login using my password, and email will then sync, 20 minutes later the issue is back.  After reading all the threads here, I am in sit back and wait mode.  Oddly this has not affected my wife's Xfinity email on my S23 Ultra, her account is working as it normally does.