Can't login to Facebook App $ instagram App

I accidentally logged out of my Facebook app and can no longer log in . It says "Login Failed" Sorry, an unexpected error occurred. Please try again later. Error code: 100. (I have an iPhone XS MAX)

I can log in to Facebook & Instagram if I do it through the browser on my phone and I can log in on my other phone as well.

I have tried turning my phone off and then on again, I have deleted the FB app and reinstalled it. And i try to reset network settings and reset all settings Nothing is working. I went into settings, then the Facebook app and I don't see anything in there that will help the situation.

Of course it is impossible to contact anyone at Facebook for help. Does anyone in here have any ideas?