The problem here seems to be that you’re using row owners/roles and a user can’t see all of the rows, hence their input can not be matched to all rows. That allows duplicates to happen.
Also, I’m not sure why you’re setting the row owner on your Row ID column. Which one is your “role” column in user profiles settings?
Nevertheless, I think you must settle for a setup of a “row owners” table for your User Profiles, and a public table for your de-duplicating purpose. Everytime a user finishes onboarding or edit their profile, add/edit a row in the public table, and check for duplicates using that table (without applying row owners).