All modern browsers are inferior in the scope of customization that Firefox legacy (prior to ver. 59.02 ) enabled.
Of course, there is that security issue...
Along with up-to-date browsers like Vivaldi (you can hack it to get multiple tab rows ) and Firefox Quantum portable (so you can also use legacy Firefox and Waterfox classic (most FF legacy extns work) then I use two profiles of Firefox ESR 59, all having their specific general use *forums, shopping..) Thank God for such tools to be use for good.
I like the current Firefox 95.0. But it’s just too slow in rendering some web pages.
Edit, that should have referenced https://ftp.mozilla.org/pub/firefox/releases/52.9.0esr/win64/en-US/Firefox%20Setup%2052.9.0esr.exe