EDIT: This has been fixed as of 1.16's full release.

I was testing out multiple resource packs that involve player animations (nothing that's game changing), and I noticed that the Elytra doesn't attach onto the player the way armor does when I activate the running animation.

This also affects Emotes in the 1.16 betas. I noticed someone use the Wave emote while wearing Elytra, and the wings were floating as if they weren't attached.

The two videos below are the best examples I could give, being a Nintendo Switch player.
I appreciate the time taken to read this.