Hey,

We are just ITM, V is new to the table. He is some unseen midstakes reg.

I would often flat here, but I think V is opening pretty wide here, so I go for a smallish 3bet (mb flat is better, idk).

Dont see a reason to 4bet shove, now is it better to call ar fold to this min4bet?

Flop is never a fold I suppose?

I think we should fold to 4bet vs random.
(although other options are quite tempting)

3b bigger pre, folding to a 4bet vs unknown and most players.

His 4b looks very strong, so fold to it (if you don't want to 3b/f, just call pre).
It's kinda pointless to discuss the flop after bad line pre, but if we somehow to got to it this way, you have to gii.

3bet sizing is fine, fold to 4bet vs unknown

Let's look at our options here. Preflop if we decide to 3b are we doing this for value or as a bluff? You mentioned that V was new and unknown so what make's you think that he is raising wide? Are you saying that because of his stack size in comparison to the rest of the table? My point is if you say he is unknown you do not know that he is raising wide. So when you 3 bet I assume your doing it for value, in that case you should call his 4 bet especially at the price he's giving you. If your 3 betting as a bluff you should normally fold but not at this price. Yes he could be very strong but even against AA you have decent equity when you call his 4 bet.

Now the benefits of flatting preflop is that to start; you keep his range wider while getting position on him throughout the rest of the hand. You also have tons of small stacks behind you that could look at this as a good spot to squeeze with a wide enough range and best of call if the betting reopens to the original raiser after a squeeze you get to see him act a second time and see if he is willing to shove the rest of his stack preflop which would save you a lot of money will less risk.

As played you can't fold now once you have gotten to this point so call/gii.

Looking at stack sizes alone, he's opening off a pretty shallow stack. Your min 3bet is fine given you have position and gives him a great spot to 4b ship. Seeing that he just clicks it back on his stack screams top of his range. Along with what others said, you have to be thinking about what you will do if he 4bets. If he had shoved, I doubt you would have posted this hand as you would have most likely folded pre. Facing the 4b you have to know you're almost never ahead here, and would only be calling cause of the odds being offered. I think best case scenario you're flipping vs JJ, and he has QQ+,AQ+ here. On the flop, you're stuck with TP 2nd kicker, so you're only beating JJ, AK (unlikely since you have a K) and any 4b bet bluffs he had (unlikely given his stack). If you still feel like you have the best hand here then ship over. If you call you're pot committed given his stack. So in conclusion, I'd prefer call (keeps his range wide open)>fold>3bet small>3bet big>5bet shove. Hope that makes sense.