I did update/upgrade of all packages and with that my firefox-esr:68.11.0esr-1~deb10u1+rpi1 got replaced with 91.some version. It is slower, youtube is not as responsive as it used to be.
What didn't I tried to get it back, nothing really worked. The main problem is that I just can't find 68 or about 68 version of firefox package for rpi. The best I could find is .deb package in http://ftp.debian.org/debian/pool/main/f/firefox-esr/. After installing which, caused firefox to crash everytime (previous version was purged).
Where do I find binaries for firefox-esr 68 or whereabouts? Or how do I revert upgrading to 91?