Btn range is wide pre, SB is narrower with 3b. Otf, SB could be cbetting, drawing to a flush or have Ax, or a set of 9's. Btn is likely calling with KhQh (making SB's flush draw less likely) or another flush draw. On turn, SB is either holding trip Aces or nines full. I doubt it's a made flush with Btn calling again. River is basically a brick as neither player is still in the hand with 5x4x.

Alternatively, SB could have gotten out of line with the the 3b and cbet with a flush draw. Btn may have called with top pair, hung around with trips while fearing a flush, and then folded to a flush after the river shove.

Confusing hand, BTN played very strangely. Don't know what he can call turn with that he can't also call river.