We do have an issue scheduled in 13.2 for Wiki diffing. However this still won't allow you to revert a change but will visually help you see the diffs line by line (just like in MRs):
I'm the PM on Wiki at GitLab - sorry to hear this happened to you! If you ever did consider moving to our free tier at GitLab, our GitHub Importer (in the docs) should handle importing the whole project including the wiki. You'd still need access to your GitHub wiki though so can't say for sure.
We do have an issue scheduled in 13.2 for Wiki diffing. However this still won't allow you to revert a change but will visually help you see the diffs line by line (just like in MRs):
https://gitlab.com/gitlab-org/gitlab/-/issues/15242
(FYI that issue is a community contribution so I can't guarantee it will ship in 13.2, but we'll try!)
I'm sure you're aware, we also have git versions of the wiki in the UI: https://docs.gitlab.com/ee/user/project/wiki/#viewing-the-hi...
Can you tell me more about your use case for versioning?