Why not try pale moon and waterfox? They’re both forks of firefox and although i’ve not tried waterfox i do use pale moon and it feels very much like a classic version of firefox before it went all bloated and confusing (i still don’t fully understand the cookies options). I would add that extension options for pale moon are kinda limited but you can still install the essentials like ublock origin and umatrix.
ETA: Having said all that… i’ve just been checking out the addons for pale moon and umatrix is no longer listed (i’m using an older version) but there is a fork for that called ematrix. This is the problem using a forked browser based on a legacy version of firefox i suppose so god bless the open source community for maintaining legacy addons.
