Super weird play. In a non-GTO way, I interpret this bet in 2 ways. A draw trying to set a price, or a strong made hand that doesn't want it to check through. Our hand isn't really strong enough to raise with someone left to act, but we can't just fold.
If we WERE to raise here, it's a weird merge spot. I can see the SB still calling with the straight draws. But there aren't many, if any, worse value hands that will call. We would look really strong raising in the middle here like we flopped a set.
Weird spot. I call. Fold to HJ raise. Otherwise, evaluate river.