grpc-swift: unavailable (14): Transport became inactive on big response

Describe the bug

1. I am using the following: 1.1. iOS (Swift) 1.2. Cocoapods

   pod 'gRPC-Swift',          '1.6.1'
   pod 'gRPC-Swift-Plugins',  '1.6.1'
   pod 'SwiftProtobuf',       '1.18.0'
   

2. I am calling a gRPC that returns approximately 40 MB of data.

let eventLoopGroup = MultiThreadedEventLoopGroup(numberOfThreads: System.coreCount)
return ClientConnection.usingPlatformAppropriateTLS(for: eventLoopGroup).withMaximumReceiveMessageLength(100 * 1024 * 1024).connect(host: host, port: port)

I use default CallOptions.

1. I have intentionally set the max. length to 100 MB as it otherwise shows an error the default 4MB are exceeded.

2. What exactly happens - I make the request, for approximately 1 minute it transfers data (seen in the Xcode Debug Navigation) and then it just stays inactive for a long period of time. Then it show the error unavailable (14): Transport became inactive.

3. A similar request with a response around 400 KB works properly.

Expected behaviour

I expect the API to return the response properly.

Additional information

I also checked the service through a gRPC client (Kreya) and the response is returned properly.