Random underwater blocks seem to be missing or flow in different directions at different depths. I did notice that the performance has finally improved back to approximately 30 fps however there are random artifacts in the water but none observed above ground.
Related issues
Attachments
Comments


Additional note. I did not observe this behavior in past snapshots to my knowledge. This included 18w10b,c,d, 11a, 14a, 15a and 16a. It was all reset in 19b so I cannot comment on the previous snapshot release.

Seed is 4478000288646156387
/tp 186 63 143

After additional observations, this has some relation to MC-129409. I did also include a screen capture of two blocks that are shown in which I am standing in and can breathe. (Note, somewhat enjoyable however as even with the turtle helmet, one must wait a really long time to be able to fully use most of this update in survival without cheats due to depths).

Instead of commenting on your issue, you can update it by hovering above the description and clicking the pen icon.