Firefox's problem is the company behind it, not the rendering engine. Firefox is actually a pretty fine browser if you pair it with uBlock Origin and neuter its wide range of user-hostile "features" and keep maintaining that as updates often introduce new "features" you'll need to disable.

What's your top three user hostile feature? Have you looked at LibreFox?

Edit: I see there is a LibreWolf and a LibreFox

See https://news.ycombinator.com/item?id=31551947.

at least according to this article from last year Arc is chromium based.

https://www.protocol.com/browser-company