[sudorandom]

They are the protobuf descriptors, which is basically the protobuf encoded version of the protobuf files. They can be optional and many plugins have options to exclude that part from the generated code. Generally, they're useful for the Server Reflection feature of gRPC and it's used for runtime reflection.

Here's a more complete description of what they are and how they're used: https://buf.build/docs/reference/descriptors.