Prevent plpsql function to be invoked with rpc

I called

alter default privileges revoke execute on functions from public;

alter default privileges revoke execute on functions from public;

alter default privileges revoke execute on functions from public;

alter default privileges revoke execute on functions from public; but my function is still available to be invoked with

supabase.rpc

supabase.rpc

supabase.rpc

supabase.rpc. What can I do to prevent a function from being accessible by users?