Commenting as an outsider to both projects, one possible motivation to fork Helix might be this PR:

https://github.com/helix-editor/helix/pull/8675

Helix was originally meant to be a "batteries included" editor without any scripting/plugins. That PR intends to change this and so there is a bit of controversy around it. Overall it looks like the PR will eventually be merged.

The Mitos fork could have be made for totally unrelated reasons. This is really just my speculation.

I don't even use an editor anymore. Just sed the source files directly via my agent.

Really? What did you not like about Helix that you get from Nano? (No judgement, I'm just curious!)

I don't have anything against Nano, but for something I use every day, I'd really miss go-to-definition, and being able to jump between sections of text quickly.

Yeah I wondered this too! The website explains the features, but from what I can tell it's just the feature set of Helix. I'm sure there's a plan behind what the forker wants to do with the project, would be awesome if the website explained!

Helix has not seen any release in a while and PRs stack.