The bug
If there are blocks above water, and these blocks are surrounded by water themselves, the water below them will convert to flowing water.
How to reproduce
Build a pool of water (at least three blocks deep)
Place a few blocks at the surface (level with the highest layer of water blocks)
Switch into spectator mode and enter those blocks, or swim in the pool
→ ❌ The water below the blocks is flowing
Linked issues
is duplicated by 2
Attachments
Comments 5
Affects 1.14.2
This bug may also be causing this: MC-151280
This is not only a visual bug. The flowing water can actually move the player or entities.