That symbol means “Ace Tanker”, a title given to players who do good on a specific tank, specifically getting more experience from one battle than 99% other players who play as that tank… Not only that, but…
I am probably making too much of a deal out of this, but this is very much unlike me. In fact, I have never done better in this game. I am proud of myself, and I now realize, that in tier 6 battles, I do good after all. Tier 8? Not so good, but I can penetrate some heavies here and there, albeit rarely.
I do consider this to be luck, still.
Btw, this beat my top-kills-in-one-battle record on the PzIV, going up from 5 to 9.