I decided to forgo the roll back. Not too savy with Apple products. Afraid I'll botch the process. I'll wait for Mozilla to come up with an upgrade that fixes the issue. But thank you again for your detailed help. I will keep that info for future needs.
May I inquire about another issue with you?
If so, I was wondering if there was any way to allow my ipad to use my ancient WD My Book Live NAS. I found OS13 software for the newer My Cloud, but I fear the My Book Live NAS is going to have the same issue with the new OS13 that Firefox is having. And WD is not likely to come up with any upgrades for the old NAS.