Disabling keychain doesn't let me use Face ID with the Southwest Airlines app

I actually work for Southwest Airlines. I contacted a co-worker that works in that area. He is the one that told me the username/password is stored in the keychain. I realize this is really not a 1P problem, but what I'm trying to figure out is how I can continue to use the keychain to get the Face ID to work, but not conflict with 1P, if that makes sense.

To answer your other questions: Yes, the login info is stored in 1P. I actually use it to log in to the app. But I would prefer to log in using Face ID, so I don't have to click on Passwords (below), which of course uses Face ID to open 1P, then fill in the username and password. I have not been able to get Face ID to work even when the keychain option is checked.

I assume that even if I un-check the "iCloud Passwords & keychain" in the "ALLOW FILLING FORM" section, the keychain is still working on the iPhone, but NOT when filling out a form. Is that right? Also, I also assume that the "iCloud Passwords & keychain" in the "SET UP VERIFICATION CODES CODES USING" section, is only for verification codes, and I should be able to check that without any 1P conflicts since I'm not using verification codes at the moment.

Thanks for trying to help me with this.