You are experiencing one of the following issues
Team members going through the sign-in process with SSO are assigned a default username such as "supply-participant-7693185", instead of their user's full name as registered in the SSO provider.
What to expect
At the moment when new users who don't have a Postman Account join a team by SSO, Postman automatically generates a default username.
Once you have joined your Postman Enterprise team by SSO, go to your profile > Edit Profile. There you can update your username.