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
Environment
openjdk version "1.8.0_212"
OpenJDK Runtime Environment (build 1.8.0_212-8u212-b01-1~deb9u1-b01)
OpenJDK 64-Bit Server VM (build 25.212-b01, mixed mode)
This is a result of a feature (client and server) infrastructure rather than a bug.