bug: HTTP/2 error code 'PROTOCOL_ERROR' (0x1)

### What version of gRPC and what language are you using?

Grpc.Net.Client version: 2.67.0

### What operating system (Linux, Windows,...) and version?

MacOs / Linux Ubuntu 24.04 LTS

### What runtime / compiler are you using (e.g. .NET Core SDK version `dotnet --info`)

```
i113855673:TopicService kurdyukov-kir$ dotnet --version
9.0.201
```

### Problem ###

```
info: Grpc.Net.Client.Internal.GrpcCall[3]
Call failed with gRPC error status. Status code: 'Internal', Message: 'Error starting gRPC call. HttpRequestException: The HTTP/2 server sent invalid data on the connection. HTTP/2 error code 'PROTOCOL_ERROR' (0x1). (HttpProtocolError) HttpProtocolException: The HTTP/2 server sent invalid data on the connection. HTTP/2 error code 'PROTOCOL_ERROR' (0x1). (HttpProtocolError)'.
System.Net.Http.HttpRequestException: The HTTP/2 server sent invalid data on the connection. HTTP/2 error code 'PROTOCOL_ERROR' (0x1). (HttpProtocolError)
---> System.Net.Http.HttpProtocolException: The HTTP/2 server sent invalid data on the connection. HTTP/2 error code 'PROTOCOL_ERROR' (0x1). (HttpProtocolError)
at System.Net.Http.Http2Connection.ThrowRequestAborted(Exception innerException)
at System.Net.Http.Http2Connection.Http2Stream.TryEnsureHeaders()
at System.Net.Http.Http2Connection.Http2Stream.ReadResponseHeadersAsync(CancellationToken cancellationToken)
at Grpc.Net.Client.Internal.StreamExtensions.ReadMessageAsync[TResponse](Stream responseStream, GrpcCall call, Func`2 deserializer, String grpcEncoding, Boolean singleMessage, CancellationToken cancellationToken)
at System.Net.Http.Http2Connection.SendAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
at System.Net.Http.Http2Connection.SendAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
at Grpc.Net.Client.Internal.GrpcCall`2.ReadMessageAsync(Stream responseStream, String grpcEncoding, Boolean singleMessage, CancellationToken cancellationToken)
at Grpc.Net.Client.Internal.HttpContentClientStreamReader`2.MoveNextCore(CancellationToken cancellationToken)
--- End of inner exception stack trace ---
at System.Net.Http.Http2Connection.SendAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
at System.Net.Http.HttpConnectionPool.SendWithVersionDetectionAndRetryAsync(HttpRequestMessage request, Boolean async, Boolean doRequestAuth, CancellationToken cancellationToken)
at System.Net.Http.DiagnosticsHandler.SendAsyncCore(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
at System.Net.Http.RedirectHandler.SendAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
at Grpc.Net.Client.Balancer.Internal.BalancerHttpHandler.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
at System.Net.Http.HttpMessageInvoker.g__SendAsyncWithTelemetry|6_0(HttpMessageHandler handler, HttpRequestMessage request, CancellationToken cancellationToken)
at Grpc.Net.Client.Internal.GrpcCall`2.RunCall(HttpRequestMessage request, Nullable`1 timeout)
```

Event Listener:
```
====== SOCKETS ERROR EVENT ======
Time: 2025-06-16T13:52:23.8749080+03:00
Source: Microsoft-Windows-DotNETRuntime
Event Id: 80
Event Lvl: Error
EventName: ExceptionThrown_V1
Keywords: 263891380633600
Opcode: Info
Task: 65454
Payload:
ExceptionType: Grpc.Core.RpcException
ExceptionMessage: Status(StatusCode="Internal", Detail="Error starting gRPC call. HttpRequestException: The HTTP/2 server sent invalid data on the connection. HTTP/2 error code 'PROTOCOL_ERROR' (0x1). (HttpProtocolError) HttpProtocolException: The HTTP/2 server sent invalid data on the connection. HTTP/2 error code 'PROTOCOL_ERROR' (0x1). (HttpProtocolError)", DebugException="System.Net.Http.HttpRequestException: The HTTP/2 server sent invalid data on the connection. HTTP/2 error code 'PROTOCOL_ERROR' (0x1). (HttpProtocolError)")
ExceptionEIP: 4423962064
ExceptionHRESULT: 2148734208
ExceptionFlags: 19
ClrInstanceID: 0
===============================
```

Start with the Grpc.Net.Client 2.67.0 call path and the System.Net.Http.Http2Connection stack entries shown in the report, using the listed .NET 9.0.201 environments. Reproduce the PROTOCOL_ERROR on macOS or Ubuntu and determine the affected server or connection conditions; done requires an identified cause and a verified fix or documented resolution.

Written by the indexing model from the issue text.