if you have multiple logins for a single website and you open bitwarden browser plugin you can click on one of them and it will fill out the credential filed of the website.
If you use the search in the plugin to find a login the auto-fill will not work anymore. If you click on the entry in the plugin it will open the information page of it. Then you need to copy and paste username and password manual in the credential field of the website.
I would expect that auto-fill after clicking an entry will work all the time.
This behaviour is also known by our users from other password managers.