Thread necromancy!!
I downloaded the Firefox Nightly 109 appimage, this is the third day I have been using it, not intensively I admit, and so far it has not frozen a single time, which is very promising.
The last version of Firefox in the Solus repository, 107, unfortunately still freezes randomly.
To Susan/SMG of the Linux Mint forums, if you are reading me, thank you very much for your efforts in solving this issue. 😃