Hello and welcome to the community,
There is no built-in functionality for this.
Maybe the easiest and safest way is to export the vault, import it into KeePassXC (which has a search-by-password feature), search and remove duplicates, export as KeePass 2 XML, purge the Bitwarden vault, and then import the KeePass 2 export.
The second method is to export in CSV format. See the discussion here.
You want to keep an exported backup, of course.