After "tech trend waves" of XML/SOAP and current JSON/REST, ProtoBuf/gRPC (or similar binary serialization) may become more broadly used since it is supported by tools for most of popular client and server platforms.
An Early Look at gRPC and ASP.NET Core 3.0 - Steve Gordon
"gRPC is a schema-first framework initially created by Google. It supports service to service communication over HTTP/2 connections. It uses the Protobuf wire transfer serialisation for lightweight, fast messaging between the services."
gRPC services with C# | Microsoft Docs
C# Quick Start – gRPC
Protocol Buffers, Avro, Thrift & MessagePack - igvita.com
"Protocol Buffers (PB) is the "language of data" at Google. Put simply, Protocol Buffers are used for serialization, RPC, and about everything in between."