I can’t log in my Facebook on my iPhone 12 Pro Max Facebook application

If you're having trouble logging into your Facebook account, here are some things you can try. Go to facebook.com/login/identify and follow the instructions. Make sure to use a computer or mobile phone that you have previously used to log into your Facebook account. Search for the account you want to recover.

I can't log in to Facebook. | Facebook Help Center

Even you may see this --> Fix a Problem | Facebook Help Center

Still not solved then --> Report a Login Issue | Facebook