Weird behaviour on Iphone.

ON my iphone, and I am going to log into an app, in this case the Guzmanygomez Mexican restaurant ordering app. (THis is app, not browser). I come to a page that asks for the email and password, below this there is a key and the word "passwords". I clock on that, it checks my face id, and I come to a screen that says "Choose a password to use for Guzman y gomez" then a line with Cancel AUtofill Password and +
- the next line is a search box, and below that a clickable "Add New Password".

I have a Guzmanygomez username/password pair in my vauit - if I go to their website with Safari - it works - but in the app I am getting this strange action - can anyone advise//?

1Password Version: IOS 8.9.7
Extension Version: Not Provided
OS Version: IOS 16.3
Browser:_ Not Provided