Librewolf: "This project is a custom and independent version of Firefox, with the primary goals of privacy, security and user freedom."
reply"Tor Browser is based on Mozilla Firefox ESR (Extended Support Release) but has been heavily modified for use with the Tor network."
Those are direct quotes from their respective web pages. Neither of them has anything to do with Chromium.
You're right, I edited my sentence to include more examples and forgot to add "or Firefox" for Tor and Librewolf. Sorry about that.
replyI would edit my comment above to clarify, but the limited edit time window for HN seems to have passed.