I have a strange quandry to present to those who play the game. Have you ever joined a match and noticed while you had not picked a class you had 4 bars and the moment you pick a class you get 3 bars? It happens to me almost every match.
The only logiccal reason I can assume this happens is because my upload is not high enough so it causes a change, when just spectating my download is more than adequate for the match to watch with out any change to the bars.
Happens when I die too, until I respawn ping is 4 bars, the moment of respawn ping is back to 3 bars.