Documentation says:

MarshalToVT() ... This function is useful e.g. when using memory pooling to re-use serialization buffers.

Could you please provide clarification on how to use it? I'm asking because protobufs are typically used with gRPC, and grpc-go's SendMsg() returns before the buffer gets put on the wire. Hence, you cannot reuse it. Here is a relevant issue: grpc/grpc-go#2159. Someone has even attempted this http://www.golangdevops.com/2019/12/31/autopool/ but it's not a solution and the finalizers have poor performance. You could find even more details here thanos-io/thanos#4609.

Are there any examples of the usage of this function? I couldn't find anything.

If I am correct then the recommendation in the README seems dangerous.