I was playing on 1.15.2 and found this issue. Tested in the latest snapshot (20w16a) and it affects too
Steps:
1. Wear elytra
2. Build something like a wall with any blocks
3. Enter F5 mode - change your camera view
4. Fly with elytra opened into these blocks
Edit:
I noticed that this happens when flying into any block in the game, and rephrased the steps.
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In F5 mode it looks like you are inside honey blocks, but in normal camera it isn't
Can you reproduce this bug in 1.16 rc1? Also, don't forget to specify whether the bug affects 1.15.2

Yeah, of course. Some screenshots from 1.16 rc1:
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Can confirm in 1.16.5 and 21w08b.
Resolved as duplicate of MC-131190, which is essentiall the same bug but has been reported for facing downwards only. That bug report will be updated to cover the sidewards case too.
What exactly is the issue here?