It seems they moved to making Ungoogled Chromium after that (you can see that Eloston, the major dev of that Chromium fork, contributed to the repo) and then maybe they just changed the repository and continued working elsewhere? That would at least explain the README.
It is so I don’t understand on what basis they wanted to sue the forking developer. At first it was trademark issues (they renamed the project from 'Braver‘ to 'Bold Browser‘) and then the developer stopped working on it at some point, however, I can‘t find any information about why they did so.
Someone tried to do it a few years back and either got threatened with a lawsuit or actually got sued by Brave because of it. The browser was called Braver; you can look it up!
This is their repository btw: https://github.com/BoldBrowser
It seems they moved to making Ungoogled Chromium after that (you can see that Eloston, the major dev of that Chromium fork, contributed to the repo) and then maybe they just changed the repository and continued working elsewhere? That would at least explain the README.