Nah, the tension was already there, since forever. It’s just that, after the failure of the misguided FFOS white elephant, they have gone back to the realization that their main source of funding will remain the browser for the foreseeable future, and that inspired (and inspires) some poor choices here and there. Eich’s departure was coincidental, imho. Quantum (which is very good) came way after he left, for example.