Some times it's triggered by conditional access policy wrt device location. We have devices set to up to 30 day session if the device stays on our company network, if you take it off site or even hotspot it onto your phone you gotta sign in or provide an MFA code
This isn't 100% true for every case. I'm able to stay signed in to multiple accounts and switch through them no problem. Doesn't work for my boss on the same accounts. (Firefox finally wins one against chrome)
I booted an old Windows VM the othere day. By old I mean last I booted it was like 6 months ago. Needed to do something that could only be done in windows. But after 3 hours of updating and 3 restarts I was finaly able to run the program I needed for 5 minutes then shut it down only to do it all over again in 6 months.... every time I do this I hate it even more. Not to mention the 7 popups I had telling me to upgrade to 11 fallowed by your system doesnt meet the minimium requirments for Windows 11.
I just wiped and set up a laptop as a favour... It forced updating Windows (to 11, possibly?) before booting. No option to skip, and no indication how much it was downloading.
Such a pain. I had to wait an hour for it when it already had a fully functional OS. What can't it download in the background and update at 3am when idle? That's what made me suspect it was as forced Windows 11 upgrade, since why else would they care to force it?