Username of person using SSO as sign in cannot be updated

Not sure if this is a bug or a feature working as intended, but here is the scenario.

Name: John Jay Smith [first name, middle name, last name] IDP: Google Mattermost Sign-in Method SSO via Google

1. User's Google account is incorrectly made with Jay Smith being put in their Last Name field and their email generated is: john.jay.smith@company.com
2. User then signs in to Mattermost via Google SSO and the account is created with email: john.jay.smith@company.com and username: john.jay.smith
3. Google Workspace admin changes the details of the user to be correct John Smith, john.smith@company.com (google by default uses the old address as an alias).

To change the email, in Mattermost, an admin needs to change it in the user account settings and have them accept via the email sent to the user. Seemingly, it doesn't see the email address change from the IDP (Google).

The username, in Mattermost, cannot be changed and does not look upstream to the IDP (Google). The only way to change the username in Mattermost is to seemingly convert the account from SSO to username/password, change the username, then have them use SSO again.

Is this working as intended, or a bug in that after changing the account the SSO is tied to, Mattermost does not update any parameters?