User 'a' submit pull request with Reviewer as users 'b' and 'c'. User 'c' detect no problems in commit and pressed 'Approved'. User 'b' detect problem in some line, and put comment on it. Then user 'a' fix problem reported and send commit into branch that automatically update Pull Request. Now users 'b' and 'c' must review this commit again. But now, user 'c' already marked this pull request as 'Approved' and must be manualy clean this flag, recheck commit, and set up 'Approved' again. It make noise in History of pull request actions.

Will be fine to have Approved on files, percentage, and also auto reset Approving from entire Pull Request and from Changed files by upcoming commits.