AD Group Permissions in SQL Server behaving differently between 2 servers

I have 2 SQL Servers running SQL Server 2019. They each have a sql login that uses windows authentication (an AD Group) "SG-GroupA" and the group has 5 windows users in it. Each of the servers has A database on it called DbFoo and the login for SG-GroupA is mapped to DbFoo and the role membership for the db is public, and db_datareader. I have verified the login exists, and the user exists on both of the databases. When A user from that group logs into the SQL Server and tries to query DbFoo, on Server A they get a result just fine. When they run the same query on Server B, they get an error "The database DBFoo is not accessible." As an additional test on Server B I created a completely new database with a single user SG-GroupA in it, and again an error is thrown when anyone tries to query a table in the DB. Performing the same test on Server A throws no errors and everything is fine. Where can I begin to debug this issue?