When modifying the PR reviewer list during a PR edit, the application currently overrides the existing list with the newly submitted one. A rare problem occurs when # User 1 opens the PR edit page to add User 3 to the reviewer list.

1. Before User 1 submits, User 2 adds themselves as a reviewer directly via the PR main page and approves the PR.
2. User 1 finally submits their edit. This action completely overrides the list, unintentionally removing User 2 along with their approval status.

So instead of a overwrite, the system should first fetch the latest reviewer list right before saving, check if any new reviewers (or approvals) were added in the interim, and keep them as it is.