I think the screenshots says everything needed. I put soul sand (I had to disable particles due to lag) under this village in a water flat world and started to see squids to freak out.
Some of them are flying out of the water and when they do that, they'll be flying up for around 5-10 sec and then they are "teleported" back to the water. After that the processs repeats. It happens mostly for naturally generated squids.
The squids stuck on the water are spawned by me and the can't move, they can only die.
And finally, squids on the right, underwater, they're stuck inside a water and literally can't move.
And after a while, all of them started to fly (if they didn't die).