When you exit a boat when leaving the boat, the texture of the entitiy disappears while still being present in the same spot. Trying to walk on the boat creates stuttering and the game considers walking on a boat as trying to fly and teleports the player.
Texture reappears when rejoining the map.

Walking on a boat when texture is present still creates stuttering effect.

This issue is not present in 1.13.2 and walking on a boat is seamless.

Exhibit A (Minecraft 1.14.2): https://streamable.com/msinm
Exhibit B (Minecraft 1.13.2): https://streamable.com/y0j7r
(Please ignore message from a friend and Bob Ross in the background. I really just wanted to test this happy little accident)