While entering water/touching flowing water while sneaking, it will make the player to unsneak, this has been happening since 1.9.0.3 Beta
This make using the Shield on water (especially flowing water) very difficult when you got attacked by many hostile mobs, this behaviour also different from Java Edition

This issue already happening before the Shield got added to the game, even if this is WAI, this should be changed as using Shield while near water (especially flowing water) in Bedrock was a pain, because the Shield will deactivated because you touching the water

How to reproduce:
1. Create a flowing water or 3x1 water hole
2. hold shift and enter it

Expected result:
Player keep their sneaking state

Observed result:
Player unsneak even though the shift key is still pressed