not sure whether my suggestion is helpful at all but I'm wondering whether EA Help (see contact details below) is able to change league passwords if it is requested by the player owning the league. did any of you (i.e. the affected players contact EA Help already and asked for modifying the password for you (in order to allow you change it to a working password afterwards)?
hope that helps. good luck!
EA Help
website: https://help.ea.com/en/contact-us/?product=madden-nfl-21&community=true
twitter: https://twitter.com/EAHelp
facebook: www.facebook.com/eahelphub
