No message received on Flow channel

[Bedotech]

Hi, thanks for your great work on AMQP implementation!
I having a problem on detect when channel enter in flow mode using RabbitMQ 3.8.15, after the channel creation i start a goroutine that check if some messages are sent from the server:

// Flow is sent to publisher channel when the Broker can't accept new messages.
notifyFlow := channel.NotifyFlow(make(chan bool))

go func() {
for {
	select {
	case flow, ok := <-notifyFlow:
		{
			if !ok {
				return
			}

			if flow {
				// On flow true resume all publishing
				publisher.lock.Unlock()
			} else {
				// On flow false stop all publishing
				publisher.lock.Lock()
			}
		}
	case <-publisher.ctx.Done():
		{
			return
		}
	}
}
}()

The channel isn't in confirm or transaction mode.
On the same channel i start publishing in loop 1 millon messages, the connection on broker side are in flow mode:

bash-5.1# rabbitmqctl list_connections
Listing connections ...
user	peer_host	peer_port	state
guest	172.20.0.1	62810	flow
bash-5.1# rabbitmqctl list_channels
Listing channels ...
pid	user	consumer_count	messages_unacknowledged
<rabbit@b929e6a54eed.1627889825.26180.20>	guest	0	0
bash-5.1#

but no notification is returned from the channel passed to NotifyFlow, any ideas?

[Bedotech]

Ok, maybe i get this, modern version of RabbitMQ use TCP back pressure, there is any way to detect di behaviour?