guardians acting weird when falling from water

i got a weird glitch or something where guardians act weird when they drop of a slope right after a water stream, it seams like they almost swim in the air. when they fall, they kinda swing up and down for a bit before they stabalize a few blocks further down. it seems like they only do it when they swim against the stream that ends right before the fall.

 

how to reproduce:

      create a water stream that ends right before a fall of around 10 blocks

      spawn guardians that swim against the waterstream

      observe as the guardians act fly/swim

 

https://www.youtube.com/watch?v=vy1CjeIji9k&feature=youtu.be