Blocks in the lowest subchunk (Y -64 to Y -49) of an otherwise void chunk regenerate when the chunk is reloaded

Steps to Reproduce:

1. Get a void world or get empty some chunks using fill command or travel to the End
2. Put some water(or lava but water faster) using fill or setblock command.
3. Let water flow until world border(y=-64).
4. Remove water source or close around.

Observed Results:

• Some of flowing waters never runs out.
• If you remove remaining flowing waters by commands or placing block by hand or using sponge they comes back when chunk reloaded.
• If you put another block instead of this bugged water block, same error repeats for that block.

Expected Results:
Water flows until it runs out.

Edit: Here is a video. Water cannot be removed(v1). If I try to put another block and remove them, the bug is inherited to the new block(v2).