Compability issue otelhttp exporter / otel receiver http(s) since 1.11.3

Grafana Alloy
1

Using 1.11.3,

telcol.exporter.otlphttp "default" {
  client {
    endpoint = "https://url:4318" 
  }
}

on the exporter side and on the receiving side

   otelcol.receiver.otlp "gateway" {
        grpc {
            endpoint = "0.0.0.0:4317"

            tls {
                cert_file = env("X")
                key_file  = env("Y")
            }
        }

        http {
            endpoint = "0.0.0.0:4318"

            tls {
                cert_file = env("X")
                key_file  = env("Y")
            }
        }

The receiving side is complaining with

Dec 01 13:58:43 adresss.com alloy[1157]: ts=2025-12-01T12:58:43.015565085Z level=error msg="http2: server: error reading preface from client 1.2.3.4:63520: bogus greeting \"POST /v1/logs HTTP/1.1\\r\\n\"" component_path=/remotecfg/cfg.default component_id=otelcol.receiver.otlp.gateway

while the sending side is

s=2025-12-01T07:17:11.232325Z level=info msg="Exporting failed. Will retry the request after interval." component_path=/componentpath component_id=otelcol.exporter.otlphttp.default error="failed to make an HTTP request: Post \"https://url.com:4318/v1/logs\": net/http: HTTP/1.x transport connection broken: malformed HTTP response \"\\x00\\x00\\x1e\\x04\\x00\\x00\\x00\\x00\\x00\\x00\\x05\\x00\\x10\\x00\\x00\\x00\\x03\\x00\\x00\\x00\\xfa\\x00\\x06\\x00\\x10\\x01@\\x00\\x01\\x00\\x00\\x10\\x00\\x00\\x04\\x00\\x10\\x00\\x00\"" interval=10.923772884s
ts=2025-12-01T07:17:09.3316242Z level=info msg="Exporting failed. Will retry the request after interval." component_path=/redactedcomponentpath component_id=otelcol.exporter.otlphttp.default error="failed to make an HTTP request: Post \"https://url.com:4318/v1/logs\": EOF" interval=9.202080394s
ts=2025-12-01T07:17:12.5306245Z level=warn msg="Sender failed" component_path=/redactedcomponentpath component_id=otelcol.processor.batch.default error="sending queue is full"

Obviously nothing is shipped. This seems like a regression.

Windows is used to send data. The client is a windows client. With 1.10.2 everything works without problems. Only 1.11.3 has been tested to show this behavior, it is not known to me if any other 1.11.x version does behave the same way.