Well, this is new and doesn't at all smell like finger printing
For context: I'm already logged in on my phone (and this PC has logged into FB before also). So, how does that work, exactly? Log out, try to log in from phone...same issue, as now BOTH devices are logged out?
Hmm. Near as I can tell, this is due to clearing cookies recently / history. Having said that, I've cleared cookies thousands of times before and been able to log in just fine. Which therefore suggests...what.. policy change server-side, not a coincidence? I'm on the same hardware, same browser, same IP. FB appears to have changed what counts as "trusted."
PS: Yeah, I hate FB too. It's the only way I have to communicate with some folks. Believe me, given the option, I'd make em all use Signal or XMPP.
Although frustrating, it is incredibly liberating to drop a contact line and delete fb.
My thoughts are if you can use facebook to message people, you can use signal, a simpler app by every standard. My 80yo grandma was one of the first across.
Bonus point of filtering out people that never reached out to you initially. They have all the details to reach you, put the ball in their court.
Good luck!