If in a water stream, flowing over fence posts or fence gates, and then brushing up against a wall the player will bounce up and down until they stop or move onto a waterless block.
This is very problematic in villager trading halls (where this exact set up is used to move villagers around and into their cells) when villagers get stuck on a waterless block (in between streams) and need to be manually shoved.

This bug was tested in survival, creative and with auto jump on and off (off initially where this first happened)