Out of all the SSO login flows Microsoft has to have the buggiest. It’s the only one I can remember routinely having issues with. Why are there so many redirects? And why doesn’t the “remember me” checkbox ever work?

It is also the only SSO flow I have ever seen that fundamentally cannot work if you have more than one account remembered on your device. So far the only way I’ve found to get it to let you log out of account A and then log into account B is to clear all cookies otherwise it gives you permission denied errors. Have no idea how it can be this horrible

I haven't seen it in a while (perhaps mostly because I'm in Google stuff way less than I used to be) but for years multiple Google sites would get in a state where its auth would route me through about twenty redirects in a loop and never actually finish authenticating me. Clearing cookies and re-logging-in from scratch was the only fix.

Youtube was always involved, somehow, for some reason, even when what I was doing wasn't connected to Youtube at all or the account I was using had never even been intentionally used with Youtube. It'd route me through a few Youtube domain names.

(Microsoft's is indeed even worse, on some of theirs [Azure Devops, looking at you] I can't use them in pinned tabs because somehow they manage to get into a totally broken state where the page won't load due to whatever's happening with their auth flow in the background, and no method of reloading the tab fixes it, and it does this every couple days—but copy-pasting the same URL to a new tab does work)

I've always assumed the billions of redirects are setting cookies so all the various systems "work" but I have given up trying to understand it.