About 6 months ago, Codeberg removed the repository for the Wikiless project, and IIRC did not offer any explanation to the developer for about 2 weeks. The reason was a Wikimedia Foundation request. Edit: https://news.ycombinator.com/item?id=33101301
I would be very surprised if this was the case - the WMF doesn't prohibit alternative front ends in any way, and it doesn't seem to do anything they'd be upset about (unless it allowed people to evade edit blocks, but that seems incredibly doubtful); if anything, surely they'd welcome a project focused on protecting the privacy of its users?
The project also doesn't actually make clear if it's actually private and not just MITMing it's own users to track them - as has been pointed out on several[0][1] privacy focused browser extensions that haphazardly included Wikiless.
[0]: https://framagit.org/tom79/nitterizeme/-/issues/61#note_1122...
[1]: https://github.com/SimonBrazell/privacy-redirect/issues/232#...