As seen in the linked screenmovie, the 1P UI interferes with SafariTP's offer to fill a texted code. The 1P entry that holds the password I'm trying to fill lies underneath the SafariTP "fill code" box. When I click on the right edge of the 1P entry, everything gets erased (note that I've already filled in the SafariTP-offered code on the first line where it says "One-time code".
SafariTP Release 111 (Safari 14.0, WebKit 15610.1.23.1.2)
1Password Version: 7.7.BETA-2 (70700002)
Extension Version: Not Provided
OS Version: macOS 10.15.6 (19G73)
Sync Type: Not Provided