Same problem here. Firefox for Mac 124.0.2, Bitwarden 2024.3.1 extension. Since a few days auto-filling forms not working any more. I’ve just tried it in Safari (where I also have the Bitwarden plugin) and it’s working perfectly there. When I try to fill in a form automatically in Firefox, the Bitwarden plugin gives an error message ‘Automatic filling failed, fill in fields by hand’ (sorry have to translate this from my language I don’t have an English version).
Update: I’ve just discovered the auto-form-filing is not working when I choose my identity from the ‘Favorites’ (you see this when you click on the Bitwarden icon in Firefox). If I go to the identities menu and use the ‘fill form’ button on the bottom, then it does work! I have un-favorite this identity and added it again to no avail, it’s not working from the favorites section. Is this a bitwarden or a firefox issue?