I have experienced a login bug with version 8 (this issue doesn't occur with version 7) - it affects both iPhone and iPad devices. I have an iPhone 12 Pro Max and an iPad Air 4 (both 2020 devices) that are fully up to date with O/S, patches, etc. I am running both v7 and v8 1Password apps on both (still using v7 due to v8 having the PIN support removed). Issue happened on both apps on both devices but v7 handled it and v8 just got locked up (in I presume a catch-22 loop).
The scenario occurs with version 8 as follows:
It would be good if v8 handled this the same way v7 does (see below), or even in a better way to that - to improve the overall UX. Obviously the issue is due to user choices (I should of logged out of all apps on all devices first; or logged into every app on every device after changing the first field and before changing the second) , but app should handle this in some way rather than leave the user hanging in a 'loop' or locked up screen with no options.
¹ my exact scenario was I was increasing the entropy & robustness of my logon for 1PW - so I changed my password first (I was upgrading my self-created 24 character passphrase to a longer randomly generated 32 character one FWIW); I opened the 1PW App on my Windows 10 PC and logged in, etc, and used this for some activity. Later in the day (6-8 hours later approx) I returned to the web vault and updated my email address (again FWIW to a unique one I have that I don't use for anything else). I logged out and back into my Windows App immediately after. However my iPhone & iPad I did not try and log into until the next day which is when the loop described above occurred (and I did not experience a similar issue on my MacBook Pro as I had temporarily deleted the apps, both v7 & v8, from there for unrelated reasons - so I had to just set these up from scratch again anyway; so this might also be an issue with macOS and even Windows apps)
NOTE that for version 7 the exact some scenario was not an issue as the app identified it was caught in a loop or such, it popped up a message to say there was an issue and that it would close and that on restart you'd need to reconfigure/set-up your account again. While this is a similar outcome (1) it provided the user a clear notification that there was both an issue and a process to resolve it - which from a UX provides non-technical people especially some reassurance, and (2) it didn't require completely deleting the app and its data; and reinstalling it again from scratch (even though this is a relatively simple process in iOS). This is obviously a superior outcome from a UX than how the new v8 app handled it.
For reference both devices have 1Password iOS App 8.9.7 and App 7.10.0. iPhone has iOS 16.1.1 and iPad has iPadOS 16.1.1.
1Password Version: 8.9.7
Extension Version: n/a
OS Version: iOS & iPadOS 16.1.1