Excellent extension! I have the family plan for Proton Pass only and after having tried some password managers, I think I have found my home. A great development is to now also have Proton Authenticator for one-time code generation, so that two-factor authentication actually stays two-factor (which it isn't if one-time password generation and passwords are handled by the same application with the same login procedures).
Great synchronisation with the Android app as well as in other browsers than Firefox, possibility to organise passwords, a shared vault in the family plan, and all end-to-end encrypted and independent from big tech - an essential extension.

keeps proposing me 4 character "passwords" and does not let me set different preferences for newly generated passwords, nor does it remember the settings used the last time. so i ALWAYS have to manually increase the size, chose words instead of fully random

I use it because of privacy, but that "1" other pass manager has much better app, much MUCH better app and addon.

+
always reliably present
easy to fill form fields
easy to save new access information
-
only the top level domain is saved, not the whole URL, which disqualifies this add-on for webdesigners & co who need to distinguish between back-end, front-end, update panel, database etc

Error message 403 forbidden. I cannot use firefox with this addon active.

Moved to ProtonPass from 1Password as I was already paying for the Proton suite. Overall, behaves decently. There's a few features I miss from 1Password, such as QR code scanning for OTP, and automatically recognizing a website's password requirements (although I prefer Proton's long text slugs, not all websites will accept them), and linking identities together, e.g. OAuth logins, or linking certain accounts to my entries for my YubiKeys. The integration with PassMail is *chef's kiss* though.