Flying into water with an elytra allows to use rockets underwater

Step to reproduce (a video is attached):
 1. Equip an elytra.
 2. Fly, using the elytra, into a large body of water.
 3. (Optional) Wait for the elytra to "stop flying animation"
 4. Use rockets to fly underwater.

You can also use rockets to fly underwater, even when momentum is totally lost from an elytra.
This issue probably relates to MC-279236.

Link for the video: https://youtu.be/NXICvS3GgFQ