Redis [BUG] Unsupported CONFIG parameter: appendfilename

When I run CONFIG GET *, there is key appendfilename on the response.

But when I want to run CONFIG SET appendfilename something it says

-ERR Unsupported CONFIG parameter: appendfilename

Additional information I am using docker image redis:alpine and redis:latest.

Comment From: oranagra

This specific config is immutable, it can only be modified at startup time (in the config file or command line arguments)