Re: Range of FF versions?
ESR 102 is deprecated and fully insecure at this point. ESR 115.9.1 (what I am using) is fully patched against this. And is also the oldest firefox version patched against this.
If you are on the ESR channel, you should UPGRADE once a year, either as soon as the new ESR lands, or ~ three months later, when the new ESR hits the automatic UPGRADE channel.
The next ESR (128) is expected to land on July 8 (I intend to install it then and there), and is expected to enter the automatic update system (and become the only ESR version) about Oct 1. It would behove you to UPGRADE if you value security.
Also, if you are on ESR, you should enable automatic security updates, as it will not mess with your stability, as the updates carry neither neither new features, nor inteface changes (i.e. no guff-storms), only security patches.