Some of the water blocks on the lake surface have been replaced with grass blocks

Dear Mojang:

After updating MC(BE) to 1.21.101, some of the water blocks on the river surface were replaced with grass blocks in one of my game saves (P1-3). The save was created with MC(BE) 1.21.90, and yesterday’s screenshot(P4) shows that the river surface was normal.

This abnormal phenomenon only occurs in loaded chunks.

For a optional sub-chunk, either all the water blocks in the sub-chunk are replaced, or nothing happens.

More details :

Game mode: Creative. Cheat enabled.

World seed: -7867673447214758489

Biome: Frozen River, surrounding with Snowy Plains.

Camara’s location: -130 130 -90 ,facing west. The river is in the southwest.

P5 shows more chunks.