Correction: To make FireFox more compatible with Yelp…

Your Firefox reported itself as version 78.15.0esr. Firefox 78 hasn't received any changes for a few years, and isn't expected to receive any in the future. Someone will need to figure out a new workaround for Yelp based on whatever its problem is with that old version, if that is possible.

Regarding support for Intel silicon, I don't think that would be discontinued any time soon. But even if, say, hypothetically, Firefox 150 for Mac stops supporting Intel silicon, old versions of Firefox wouldn't be affected.