Near water, usually running water, I'll sometimes walk over a block and float up about half a block.  This has happened to me at a wheat farm. Directly adjacent to the water (running water), I'll float up half a block for apparently no reason. It seems impossible to get rid of the issue, so I just live with it.

I THINK this is related to MCPE-33641, but I wanted to make sure the Minecraft team was aware of this.

I think the same thing might be happening with the guardians. The guardians might be interacting with a non-existent water block, causing them to swim in mid-air.

I used sponges to remove all water around my guardian farm "tube" where guardians fall and die. The guardians still float at that same location. BUT I ALSO NOTICED, there are blocks near the tube where if I walk, I'll float up about half a block. It's almost as if there's invisible water there.