Librewolf is Gecko and Brave has a big team and a lot of money, sponsored by Facebook and some crypto companies., even so the Brave chromium version is behind of the current from Chrome. There is an blogpost from one of the Vivaldi devs, explaining the work to make and maintain a Chromium fork

https://yngve.vivaldi.net/sooo-you-say-you-want-to-maintain-a-chromium-fork/