PokerStars - $0.16 NL (6 max) - Holdem - 6 players
Hand converted by PokerTracker 4

BTN: $16.86 (VPIP: 21.25, PFR: 17.50, 3Bet Preflop: 3.45, Hands: 80)
SB: $4.50 (VPIP: 39.36, PFR: 2.13, 3Bet Preflop: 0.00, Hands: 95)
BB: $16.24 (VPIP: 20.85, PFR: 17.22, 3Bet Preflop: 3.25, Hands: 980)
UTG: $16.00 (VPIP: 20.00, PFR: 20.00, 3Bet Preflop: 0.00, Hands: 5)
MP: $21.09 (VPIP: 21.15, PFR: 17.31, 3Bet Preflop: 0.00, Hands: 54)
Hero (CO): $19.79

SB posts SB $0.08, BB posts BB $0.16

Pre Flop: (pot: $0.24) Hero has K A

UTG raises to $0.48, fold, Hero raises to $1.60, BTN raises to $3.84, fold, fold, fold, Hero calls $2.24

Flop: ($8.40, 2 players) 5 2 2
Hero checks, BTN bets $4.01, Hero?

I'm not 100% that preflop is okay, sample size is only 80 hands so that's a concern, but at the time 4bet folding seems awful, shoving seemed bad with his 3bet % and calling leaves flop situations like the one that followed.

What should I be doing on this flop?

Check/fold.

I would flat pre vs unknown UTG.
As played flatting 4bet isn't horrible but it is going to be tricky when we don't know how he plays. Think I would just rip it in and hope for the best, sample size is small enough that his 3bet/4bet stats will be misleading.
Shouldn't really x/f this flop if you think that flatting pre is a good option.

flat pre, as played fold, but rly shouldnt be in this spot

Yeah flat the UTG raise pre. Tbh I'm just folding to the cold 4bet from the BTN who appears to be a tight 3bettor from initial stats (and even though it's a bit small to say, the fact is cold 4bets are usually the nuts anyway, even from guys with a 6-8% 3bet stat). Especially given positions - he just cold 4bet a guy who 3bet an UTG open.