flatting 3bet 165bb deep

This isn't good spot to call 3bet w SC, or even OR, so fold preflop.

First, it is not a 3b but a squeeze.
Second, when that deep you can call when HU, but here what bothers me is the still-to-act shortstack MP.

This is fold for me 100bb deep and yeah like you said I probably should fold also 165bb deep. Was just not sure.

And yeah sorry I used the wrong term it is a squeeze.

Do you have a calling range here or do you always 4b or fold?

You will be oop so better 4b for me.

Yeah I'm not a big fan of playing OOP being that passive. And as pointed by nitrol the short stacked MP could be super annoying, either 4b or fold imo.

With 100bb stack this is a standard fold for me. When deep I think we can play this but shortstack MP worries me. Since we would be playing OOP I think it is better to 4bet than call.

fold pre is more than a std

Fold pre, suited connectors need position, so you can pinch a few extra pots / get paid more often when you hit. Also, people should be gunshy about 3betting your UTG opens. If you are opening your full CO range from UTG, villains can 3bet you from position with a huge range for autoprofit.

Though I do enjoy limp-raising with 78s in this spot to represent aces. Not that I ever limp-raise aces. But I'll bet there are notes out there that say I must have.