theres something wrong with the replayer , you are on the big blind right? not utg.

very tough spot imo. he could value shove worst like smaller flushes , trips (maybe, being a sne he might be playing 24 tables and not even noticed a 3d diamond hit the river.)  when he check/call turn , he could be just letting your floats give a shot at the pot but the k is the worst bluffing card in his view so he would probably value bet this turn and not go for the c/c line.  the tough part is that due to bvb , ranges are so much wider, that he could just check call a boat or quads in this spot and if it was utg1 vs cutoff he could just bet/bet/jam a value hand... but a sigh good fold imo. against his value range your not doing that well.

This is a pretty tough spot. My only problem with him having a hand better than Qhigh flush is the fact that if he does have a boat/higherflush he loses a lot of showdown value by checking on the river, given the probabilities that you will check back. For me personally, 85% of the time I bet out the river to get value if I have a monster, or I shove all in on the river when im first to act to induce a call by convincing the opponent that im using fold equity against them (I use this against really good players, and alot of times they call). Checking with the nuts only works here if he has a good read on your style and hoped you caught something on the turn.. For me personally I think you should've called. The pot odds with the Qflush were good enough. Also, most Highly skilled players online prey on fear and playing very aggressive in high buy-in tourneys allows them to push players with stronger hands out of pots. I would've called but thats just my position.