As indicated in this answer, it's possible for a user to approve an edit by electing to first improve it, then submitting no additional changes. This validates the suggested edit, but because no additional changes are made by the "improver", the secondary revision is not saved as per normal rules.
This can be used on sites that require multiple approvers to circumvent the number of required approvers. And, worse and more severe, regardless of the approver requirements the approval is attributed to the Community user only. I don't know if the devs can actually see the failed revision submission or if they otherwise track the "improver", but it's otherwise a very big hole: the person approving the edit is effectively anonymous - a malicious editor could potentially propose an edit without logging in, and then log in to improve/approve it, resulting in a completely anonymous edit being made.