When jumping off a high spot and activating the elytra, in some cases the elytra deactivated without any warning or input. I first experienced this when jumping off of a platform at height limit (this might be the reason) and wasn't able to react in time, but after that it kept happening. I didn't notice a pattern of it deactivating at a certain velocity, but that could also be the case. This could be very detrimental for players as this results in instant death when it occurs.

I have more video examples but it exceeds the video limit