Since season 11 launched, more times than not, valks jet pack is practically silent. I have died for this reason too many times to keep count. I replied to another not long ago here whom voiced the same problem. Before season 11, Valk if in a POI next to the one I was in if used, was vaint....but still could hear it enough to say to my teammate "there is a Valk over there" and ping the POI next to us.
Now since season 11, valk can use it 5 feet from me to jet over my head and land directly behind me with either the slightest vaint sound, making me feel she is a ways away....or absolutely no sound what so ever.