This is happening to me too (Bedrock/Windows 10 V1.17.11).
I think this can also affect the player. 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. This has happened to me at a wheat farm as well. 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 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.
Reply from @unknown: what you also noticed is MCPE-51142.
This is happening to me too (Bedrock/Windows 10 V1.17.11).
I think this can also affect the player. 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. This has happened to me at a wheat farm as well. 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 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.
Reply from @unknown: what you also noticed is MCPE-51142.