2 pair in a 3bet pot with a draw on the board

Preflop: What's your sb vs utg 3bet range? I personally don't play A4s in that spot.

Flop: No information, but his 3bet calling range should be fairly nitty. Some pp's, AK, maybe AQs and maybe some s.c.

Now let's give him a wide range, with 65s+, 22+ and AKo. I assume he would raise flop or raise turn with a set, so he probably has AK or a fd.

Vs {AK, 65s+ (spades)} we have 57% equity, so it's an easy value bet. I don't believe he's folding TPTK in a 3bet pot to a river bet.

Also, he might be a bit tighter, and obviously not call all those s.c. utg vs sb, so I think our equity should be even better. Since you do not fold the river and pay off his flushes, you might as well jam it to get called by AK, which otherwise would probably check back.

PS: I just checked the result. With that result you can make a note on villain, that he defends way too wide vs sb 3bet. You can just 3bet linear, probably AJs+ and bet for value.

Easy triple barrel, so many TPGK hands you have value against.

A4s imo is good 3bet hand vs UTG when we are IP, OOP its probably more preferable to 3bet 89s type hand because we will get flatted more when villain is IP and have better playability because we are not dominated.

I will also make 3 barrel here. The flush in not much possible and villain has a lot Ax combos to pay you off.
I totally agree with metza about 3 betting A4s OOP. SCs is way better.