Ok so my tablet did the ios15 update…
Yes i have 2 accounts both linked to Facebook, after the update I was stuck in one acct, finally got out of it and to main play acct but am now having issues getting into other acct.
it’s not giving the choice of which acct I want to log in to like before .
Im using the same device as always and have had no trouble until today. Which leads me to think it’s Apples update, but who know Facebook could’ve updated and I know tripeaks released a update recently which I have those update installed automatically so it could be a number of thing.
That’s what I’m trying to figure out.
Is there anyone having the issues of switching between accts.
I’ve had this issue on other games because it’s logged you in with the game centre iOS and even if you log out of fb it stays logged in to game centre 
Question, do you sign into FB via their app or do you sign in via a browser? Wondering if this makes a difference. I checked my 2nd account [which I don’t really use], and cleared my browser data. I went to check if I was still logged in since still have all my stuff in game, but it doesn’t seem like I am. When I try to log in however [down loaded FB app to test it out] it wouldn’t let me anyway, so not even sure now if having the FB app will make a difference. Tapping to sign into FB isn’t working for me.
I’m not sure I know what the Game Center is …
Iv never used that…that I know of🤷🏻♀️
For Samsung users, they have Game Launcher, but I do not have issues with any of my other games, but then again I log into Facebook using the Facebook app and do not use any of the internet browsers [Chrome, Safari, etc.].