Desktop app and extension don't integrate

Can you tell me a little more about what you mean by "breaking again"? Are you unable to unlock 1Password in Safari? Or do you see a blank pop-up?

Sure, the extension appears in the Safari toolbar with a lock on it, clicking it shows the popover but with either a "loading" spinner or an "Open 1Password" button. Clicking the button does nothing though. The webpages don't show the logo in text fields and no form of autofilling seems to work. I can open the 1P app itself though, even leaving it open and unlocked doesn't seem to help the extension. I can of course copy/paste my credentials. I also get the on-page presentation for Passkeys, and it has a button that says "Unlock 1Password" (i believe) but clicking it does nothing as well.

Has the issue reoccured after updating to macOS 14.2 beta 3 or later and which version of macOS are you running right now?

I'm currently running 14.2 Beta 4 (23C63) and the extension was unable to access/connect to the app. As with other times deleting an hour of browser history fixes it (i also quit both 1P and Safari and re-opened them, although it appeared to be working without doing that). I just lived with this issue since it appeared (knowing i was using betas) and eventually came here and found out about the workaround of deleting some history. But each time it eventually goes back to not working -- I haven't recorded if it's only after Beta updates or some other event. I just know that eventually I find it's not working again. I can't confirm that I did this fix after beta 3, I only know the problem was still here even though I was on beta 4. I'll keep an eye on it and post here again if it reverts and stops working.