Since I’ve been using password managers for a while now (KeePass & LastPass) I keep noticing that some sites will block you from pasting into their password fields. So no I’m not typing in that randomly generated 64 character password ever.
A bit of googling found a Firefox extension that disables clipboard events, but it’s now built into Firefox itself.
Paste this into the URL bar:
then change this key from true to FALSE
Now JS in page can’t see clipboard related events and thus can’t stop you from pasting into password fields among other things.
Obviously beware that this may cause issues on some sites, but I’d rather deal with that if it happens than be annoyed by not being able to paste into password fields.