The impact of the academic year on the quality of AdMob advertising

I want to show you an interesting screenshot (open the image, otherwise it was cropped a little):

Campaign Parameters:Geotargeting: countries of the former USSR

Number of clicks: constant, 1000 per day

CPC: fixed, the same for all ads

It turns out that, other things being equal, with the beginning of the school year, the quality of the advertising campaign drops to one and a half times. And you do not have such a thing?