40BB pot crazyness

KillerDucky PokerStars 2/4 Hold'em (10 handed) FTR converter on zerodivide.cx

Preflop: Hero is CO with 2h, 2d.
UTG raises, 1 fold, UTG+2 (Maniac)/ 3-bets, 1 fold, MP2 caps, 2 folds, Button calls, 2 folds, UTG calls, UTG+2 =#A500AF(Maniac)/ calls.

Flop: (17.50 SB) 7d, 8s, Qd (4 players)
UTG checks, Maniac bets, MP2 raises, Button calls, UTG calls, Maniac 3-bets, MP2 caps, Button calls, UTG calls, Maniac calls.

Turn: (16.75 BB) Ad (4 players)
UTG bets, Maniac raises, MP2 calls, Button 3-bets, UTG calls, Maniac caps, MP2 calls, Button calls, UTG calls.

River: (32.75 BB) 4s (4 players)
UTG checks, Maniac bets, MP2 calls, Button raises, UTG calls, Maniac calls, MP2 folds.

Final Pot: 39.75 BB

Results in white below:
UTG has 9d 6d (flush, ace high).
Maniac has Ac Kh (one pair, aces).
Button has 5d 4d (flush, ace high).
Outcome: UTG wins 39.75 BB.