Upstream account provider returned "<reducted>" as username, which is not linked to that upstream account

**Describe the bug**
User could not login into the system.

**To Reproduce**
Steps to reproduce the behavior:
1. Go to mas_domain_Name
2. Click on 'My account'
4. See error: `Upstream account provider returned "" as username, which is not linked to that upstream account` (and `Localpart template returned an existing username username= user_id=` on the server side)

**Expected behavior**
MAS to work, as expected, and as it works for everyone else.

**Screenshots**
N/A

Any system.

**Additional context**
For some reason, `upstream_oauth_links.user_id` was not there - I worked around that issue by `UPDATE upstream_oauth_links SET user_id='user_id_from_users_table' where subject='';` - hope that was correct.

I can't see how / why this user encountered the issue - the only difference from the others that I see, it's that he was not logging in for quite a while (90+ days).