UTG+1 was a hugely winning player at $20 abi according to OPR. He was 28/14 3bet% of 5 over 37 hands.

SB was a nitty fish. 9/6 with 3bet% of 7 over 100 hands.

I think UTG+1's flatting range is fairly strong here. I think he has a lot of PPs, maybe some suited broadways (prolly not many tho), but I think he could have the top of his range too (AA-JJ and AQ+). Things get kinda awkward when SB jams because I think flatting announces that we're not that strong when we're 45x deep with UTG+1 (and we pretty much have to fold if he raises) and I think 4betting gets a bit dicey if UTG+1 does anything other than folding.

How do we proceed? Folding seems ridiculous getting 5-1 against a 4x jam, but all the other options seem kinda bad too? Do we 4bet/fold and play fit or fold postflop if he calls and we miss? If we make it around 100-110K and he calls, there's gonna be 250-270K in the pot and we're gonna have like 350 behind, so it's kinda gross oop. 4bet/folding is also kinda gross on a 45x stack and we can't possibly 4bet/call. What to do?

i dont mind flatting, i think that makes us look strong

jamming might be ok too, I think he 3bs JJ+, AK pre and would fold AQ,TT etc to a rejam

Std call
Go for 1street of value on Jxx Axx. Don't c/x better hands since his blufffactor is low (hand goes to showdown)