Sculk shriekers can be pushed by a piston, which is not in parity with Java Edition.
How to Reproduce
Place a piston
Place a sculk shrieker on the front/top face of the piston
Push the piston with a lever/button
Observed Result
Sculk shrieker can be pushed by a piston
Expected Result
Sculk shrieker cannot be pushed by a piston
This is a duplicate of your previous report, MCPE-153209, which is resolved as a duplicate of MCPE-116030.