I was walking in my singleplayer world and then somehow. I was walking slower for some reason, and my auto jump made me jump on top of some invisible block I can't break or see using F3, its no barrier. It just is like invisible. I don't understand what in the world is that.

And using commands I summoned a falling block and then it is flying. (it also shows the particles) Something is going crazy. (I'm sorry I can't upload because max is 10MB so I will make an unlisted video.) (https://youtu.be/WC-xKKVgMn4)