When I use "Open and Fill" on a URL field in the main 1Password app, I get a pop up (pop down?) from the menu bar 1Password mini with my list of favourites displayed. In times long past it used to open the website...
This has been the case for quite a time - months. It has persisted through a Catalina installation (format and reinstall, fresh install of the apps, but restore the user account).
Screenshot to show the issue - click the "open and fill" to get
1Password Version: 1Password 7 Version 7.3.2 (70302004) 1Password Sto
Extension Version: 22.214.171.124
OS Version: OS X 10.15
Sync Type: iCloud/1PW account