This bug has existed since the implementation of elytras I believe but the way elytras work in 1.15.2 has made desync happen even more. Essentially, a player with high ping can sometimes not correctly inform the server that they have toggled gliding, yet clientside they are. This is especially frequent when they are "elytra-hopping" (jumping and spamming spacebar to hop with elytra) This is problematic as a lot of server anti-cheats see this as illegal movement, as the player flies very unexpectedly without being in a gliding state. If you could somehow fix this, I would be very grateful. Thank you for reading. Here is an example of what this desync looks like to the client compared to the server: https://youtu.be/duzIJVv1JSw