Also think that the nerf is needed, but ......
For me it does not feels completely right. This because (almost) all Battle Path end rewards vehicles get nerfed when there are " a substantial amount" of players have it, perform with it and (maybe) will be the example for other players to get it asap (see how good this end reward tank, in this example the T15 Kinzhal, is. You better should do your best (or pay) to get this tank).
And then, after some time, AW has some " in-depth inquirements" who reveals' that this reward tankT15 is overpowered. And it always happens after a substantial time frame (hear AW stating " we need data" and in some way I understand that). But they never find it in the test period, and you could say, that after so much nerfing in the past, you know what you should investigate before releasing it. And that's what I personally find strange and or incorrect.
Players tried to get a tank based on their characteristics and after acquiring it, get something adjusted / different afterwards.