88 BB vs UTG deep Zoom

With a quick glance looks quite standard. You hit a set and you stack off. Ofc it is just a bottom set but I believe villain could stack off here with AA,KK,QJ. Wouldn't be impossible if he stacked off with something like AsKs KsTs or a pair+draw like QT and so on.

If T9s,JJ and QQ beat you that is only 10 combos. If he would stack off only with AA and QJs you would still be ahead.

I see him shoving the flop with a combo draw (flushdraw + straightdraw), trying to maximize his equity. KTs with the second nutflush and a OESD is very likely.
A bigger set is always possible, like JJ or QQ once he opened from UTG.
That is such a connected board that I'd also 4bet like you did instead of calling his 3bet. A lot of cards may come OTT and OTR that could complicate your situation. Your hand is too strong to fold here, especially because I believe his range his made mostly of draws.
Against this range: JJ, QQ, QJs, T9s, KTs, AKs you're 63% favorite OTF.

It is perfectly norm to stack off with a set here. Plus you have a redraw.

I like it. I'll play the same way. You can never fold, unless you have very specific reads for the villain