One thing every junior web developer learns is how to implement a login system.
They may not make it the most secure, but it works.
It boggles my mind how Microsoft still don't know how to make a login that works consistently.
Every Microsoft login page requires like 30 redirections to work.
The Teams app on my PC fails to login at least once a week, just because another Microsoft app is logged in using the same account (usually office), but Windows is not.
Microsoft needs to take it's head out of it's ass and BEG Google to teach them how to make a decent login system.