Gray water particles when sponge absorbs water

When water is absorbed by the sponge, gray particles appear

Steps to reproduce:

1. Place a water source.
2. Soak up the water with a sponge (while watching the particles near the sponge).

Observed results:
When absorbed by water, the sponge will release gray water particles.

Expected results:
The particles should be blue when absorbed by the sponge.

Image:

Original Description
1. When water is sucked by a sponge, it produces a gray particle.
2. Water replaces a square and is sucked into a sponge to create a phantom block.