Why transformer: superjson breaks the POST ?

 "message": "[\n  {\n    \"code\": \"invalid_type\",\n    \"expected\": \"object\",\n    \"received\": \"undefined\",\n    \"path\": [],\n    \"message\": \"Required\"\n  }\n]",
            "code": -32600,
            "data": {
                "code": "BAD_REQUEST",
                "httpStatus": 400,

create: publicProcedure
    .input(z.object({ title: z.string() }))
    .mutation(({ input, ctx }) => {
      const id = db.posts.length + 1;
      const post = { id, ...input };
      db.posts.push(post);
      return post;
    }),