In 2.2.x it is there. Anyway: swiping right (with thumb or two fingers) is a feasible solution - you only have to know about it. (At least on iOS 17.x)
from what i remember reading it was added when pwa support was added for ios devices. though i could not find that mention again.
when i updated my 2.2.5 build to a more recent build, it arrived on it and was visible on androids as well. though i never saw it here on xf community pwa which was quite weird. seeing that back button was annoying initially but i learnt to ignore it eventually.
it disappeared when i installed beta builds and haven't seen it so far as you mentioned. i am sort of fine in either case. though i would prefer if it was optional on androids at least.
If I was a betting man, and a drinking man, I'd happily bet a pint that this won't happen. As it is, I'll just say that if it happens, I'll eat my hat. Albeit an edible chocolate flavour hat.