If you zoom in on individual days there are fluctuations up and down. Eyeballing it, I'm willing to believe that there has been a decline, but there is also a reasonable chance that it is simply a statistical fluctuation. More time will tell.
WotR is still doing better (approval wise) that Kingmaker at this same time in its life.
For what it is worth, I have not encountered game stopping bugs in either game, and I did play kingmaker at release too (not trying to claim they don't exist! they just don't affect everybody).
