It happens. Sometimes, it happens in clusters. If you start speculating about conspiracy theories you’re going to sound pretty silly, so just accept that it’s an unlucky coincidence. Sometime in the near future, you’ll go an unusually long time *without *running into someone else’s 1-card flush, though of course you won’t notice it.
ETA: By the way, a flush draw is a flush draw. Hitting a flush when you have two Spades in your hand and two on the board is no more likely than hitting it with one Spade in your hand and three on the board. Of course, you’re more likely to acquire a flush draw in the first place if your hand is suited, but think of all the times there are three to a suit on the board by the turn. One-card flush draws happen all the time.
If you were playing for virtual money in the situations in the OP, then I’m not the least bit surprised you got sucked out on. If it doesn’t cost them anything of value, then why not play “any two?” Then should the flop come out three to a suit, anybody with a high suited card is going to chase you down no matter how much you bet. Because it doesn’t cost them anything of value.
Happens all the time. Tonight, down to final 3 in a SnG, I got all-in against a donk - my 66 (I think) against his J2o. He hits 2 pair on the flop, and a boat on the river. You just can’t outsmart dumb luck.
Free rolls are not good examples of good poker play. A lot of players go all-in on the first hand so they can move on to the next one if lightning doesn’t strike.