The bug
When at certain y-levels, looking straight up causes the lava fog to unrender. It only occurs with lava, it does not affect water. This seems to happen in 1 block intervals around the .35 decimal mark. Slightly looking downward returns the fog as normal.
Attachments
Comments 5
This bug has nothing to do with MC-206610, I think. The issue can be seen best by simultaneously flying up and looking up in deep lava. Every block at around .3 the lava fog disappears and makes the screen flicker due to this.
Removed the screenshots as these are not clearly demonstrating the issue and may be misleading. Added a video instead.
I did notice the flickering while testing, thanks for adding the video.
I can also check at which angles the fog appears and disappears at if you need
Can confirm in 21w14a. It appears that this does indeed have nothing to do with MC-206610.
It appears that the fog unrenders above 0.33 and at/below 0.38 at 1 block intervals. For the sake of the next explanation, I'll call these areas "pockets". The area in which you can look while the fog is unrendered expands the higher up in the pocket you are. Towards the bottom, the area is restricted to only -90 in the vertical orientation axis. Towards the top, the area expands to just above -55 on the vertical orientation axis. This may be somewhat irrelevant but still adding it in case it aids in fixing the issue.
Would MC-206610, happen to describe your issue?