Sorry, nevermind. It happens WHENEVER I move a block using a piston, not only when it's next to water, which has already been reported by another user.
MCPE-33292
Moving a block next to water crashes the game
Resolved
Duplicate
0
(Unassigned)
Unconfirmed
Phone - Android - Samsung Other (Specify in description)
Android 7.0
1.5.0.1
Retrieved
Duplicate of MCPE-33072