I can't access my account with Firefox or Brave but can with Librewolf

Pretty much says it.  

When I sign in, I enter my user name (as I have been doing for the past many years) and the browser returns me to the user name entry page instead of moving on to the password entry.  Same behavior on Firefox and Brave on multiple machines.  This has been going on for a couple of months and I get around it by using Librewolf.  Without going through every setting on all three browsers, can I be directed to the likely candidate settings?