[Closed] PLO25 T987s

I don't think you should have c/c flop. As you said, you risk giving him a free card to a flush draw you don't have. Your straight is also very vulnerable... any diamond, Q, 9 or 8 on the turn might make you think twice about your hand in case you face any aggression. If you plan to shove anyway against his 40BB stack, you should try to do that as soon as possible by leading and then shoving if raised on the flop. Being that shallow he might call your shove with two pair or top pair/SD + FD, and in both cases you are a favorite.

Your check on the turn is also bad, once he might have checked behind in order to catch a diamond draw, if he had it. I think this is a hand to play fast and obvious against his stack.

If he was 100BB+ deep, I still think you should lead the flop. If he just calls, you lead the turn again on a safe card. If he raises your flop bet, just call and then shove the rest of your stack if a safe card hits the turn. Otherwise you can check/fold.

An UTG raise preflop shows your opponent has something he likes, could be AA or KK, could be AKQ or 6789ds.

I would expect villain to cbet this hand and I think for metagame reasons it's okay to check to him, if he checks behind then he has absolutely nothing at all (at best he has something like AAKx and takes the free card with his gutshot.
If he does check I bet 100% of turn cards since I don't expect any of them to hit his range.

On the flop I think he bets all his flush draws and AKQx/KQ9x hands, plus obviously sets and straights here, as well as probably JTxx and KQJx

A check raise is best given you can make it $4.50 leaving $5.50 for the turn into an almost $11 pot (where you are both pot committed and given you have 2 pair, you're stacking off on pretty much all turn cards.