At present, https://musicbrainz.org/relationship/a3005666-a872-32c3-ad06-98af558e99b0 does not describe what a "cover" is with regard to the "cover" attribute for the "recording of" relationship. It would be tremendously helpful to have a description to avoid situations such as this.
Such a description would look something like this:
A cover recording is a recording of a work by an artist other than the artist who recorded the first released recording of that work.
Example: Dolly Parton recorded the first released recording of "I Will Always Love You". Whitney Houston later released a cover of the same song.