Mine: require setting a URL to support password managers. You download an app, go to login, tap the password field, and open Bitwarden. Does it find your login? Half the time, nope! The dev didn’t tell Apple one time what their URL is, so everyone now has to search their password manager every time.
Be less clever with payment information, including billing address. I suppose that was helpful in the Olden days but now that Apple Wallet can autofill, get out of the way.