I use the latest https://archive.mozilla.org/pub/firefox/releases/85.0/win32/
Yes, 32bit on a W7 64bit-System (bit more ''strechy'' on my USB-Tethering-Connection)
Plus some USER.JS modifications and Profiles with different Privacy Settings and Add-Ons.
Plus ESR for some Websites https://archive.mozilla.org/pub/firefox/releases/78.7.0esr/