Sending around protobufs encoded as JSON makes reverse engineering much easier than you might imagine. I can just imagine what the internal .proto files must look like - especially the arrangement/ordering of fields which tells you how the software design evolved. Two fields with tags next to eachother? They're probably part of the same feature and they were added by the same person as part of the same commit.
Just curious, how does Protobuf make it easier? Easier than Json? Protobuf doesn’t even include field names or readable descriptors - unless of course you are talking about reading client side JS