Did you receive an email from Mattermost about YOUR DUPLICATE ACCOUNTS HAVE BEEN UPDATED?
Would you mind running these sql queries so we can see the user mappings? You can obfuscate/truncate the data.
SELECT Id, Username, Email, AuthData, AuthService FROM Users where Email = 'username@example.com';
SELECT Id, Username, Email, AuthData, AuthService FROM Users WHERE Username = 'username';
SELECT Id, Username, Email, AuthData, AuthService FROM Users WHERE Email LIKE '%username%';Would you mind searching your log files for a line like the following? maybe greping for your email?
modified user_id=xxxx, changed email from=user@example.com to=user+team@examplecom, changed username from=user to user+team changed roles from= to=