Anyway, that is not the point.
Do you want to find a solution to your troubles or do you want to lament about big bad Google.
60% less traffic == 60% less earnings. Two thirds of the problem lies with a loss in traffic. That would be the first issue I would address, if I were in your situation.
The remaining 30% drop is likely to do with an increase in mobile traffic across the board.
Where is your revenue coming from desktop vs mobile?
How does the portion of mobile revenue compare to the portion of mobile traffic?
What is difference between your active viewable for mobile vs desktop?
How are your ads implemented on mobile?
You may well be impacted by smart pricing, but I would doubt that. If you are only getting a few clicks a day there would be no alarm bells ringing at Adsense. My understanding is that smart pricing is used in situations when a publishers is providing many clicks to advertisers but those click convert a rate well below the norm, ie there is something fishy going on but they can't prove it.
As for getting a big click and then nothing behavior. I provided a logical explanation (see last post on page 3 of this thread) to someone else who came up with the same theory. Again, your lack of traffic and earnings makes your claim highly unlikely. What interest does Google have in spending time and resources to prevent publishers that are not making money from making even less money.
Finally, magician's recommendation to use the ad-balancer is a good one. With low traffic and few clicks, there is a high probability of being served spammy ads. These ads erode the trust of your users. So users will be less likely to click on a legitimate (high paying ad) if they are surrounded by spammy ones.