In that case it's simpler to find the right password entry, click edit on it and add the current domain to the list of domains it keeps for the entry. That way you won't need to mess with the copy/paste button.

I use Bitwarden myself and I only need the copy/paste button for stuff like email and WiFi passwords. If you're manually copying and pasting data, you're probably overlooking one of the many (sometimes not clearly indicated) features Bitwarden has.

Hope this helps!