As soon as I see this flop I'm typically in triple barrel mode. Great equity, low showdown. Bet/bet/bet is good improve or not.
He donk bets river here, and we have to call with straight-combos. Even possibly some stuff like AA/TT, but generally not too much wider without a specific read. He obviously has a lot of flushes, but not only flushes, plus we get some pot-odds.