When I'm actively chatting on the desktop app, if I get notifications in another chat, my phone rings for every notification, even though I'm active on the Desktop.
There should be an idle period before the notifications get sent to all devices.
Also if notifications are disabled on the desktop, and I'm active on the desktop, notifications should not be sent to my mobile.
Open any chat, start talking to people.
Receive messages on another chat, and don't open them instantly.
My phone rings for the other chat new message notification.
Telegram Android 7.4.2 (22277), OnePlus OnePlus6T, 10 Q (29)
Desktop app as well.