Since the Firefox Nightly update I activate on 20th May, my webpages were unable to load when though they are connected, and it didn't work after restoring old Firefox profile after doing a refresh on Firefox.
So I tried next to disable and narrow down the add-on causing the issue and found that the page loads after 1Password extension is disabled. The issue comes back if I re-enable it again.
Firefox Browser details
Firefox Nightly version 78.0a1 (2020-05-19) 64-bit
1Password Version: 7.4.767
Extension Version: 22.214.171.124
OS Version: Windows 10 64bit Version 1903 (Build 18362.10024)
Sync Type: Not Provided