the people don't validate because this penalization also drop the coverage to 20% or less... so now you can see.
Ah! Okay then. So it's more like the coverage which is causing your loss of CTR/Earning than the double click itself. That's different.
So if there is effectively a global penalization, then there are several reasons, that I guess you were already exploring.
Before this penalty, was was the "normal" CTR and coverage?
Penalty can come because of a high bounce rate. People clicking on ads, and coming back, or closing the browser. There are several reasons for this:
- accidental clicks,
- misleading placement (both can be related),
- too many ads, (dilute the quality of ads)
- misleading ads,
- low quality advertisers. (deceptive)
- profile of your visitors,
For accidental clicks and misleading placement, be sure to review your page layout, or better, have your pages reviewed by an outside eye. You may feel your ad placements are fine, but you are not objective about your own work, and also because you are used to see your own pages.
You also have to control the quality of ads showing at your site. Misleading ad creatives can account for higher bounce rate, and let Adsense believe your site not delivering quality visitors or has misleading placement. So everyday, use the ad review center of Adsense, to check each creative, and do not hesitate to block those which are misleading, clickbait, or anything of low quality and uninteresting.
If a give ad creative is "too" appealing, lot of people will click on it, but, if the landing page is deceitful or unrelated to the creative they'll bounce back. This is a vicious circle, because, lot of clicks (good CTR), will make adsense to serve this ad more often to your site, which in return will cause an increase of bounce back, and downgrade your adsense quality score.
The profile of your visitors is also important, by profile, it means both the tracking history that Google has about them, as well as their behavior. You can have a site with millions of visitors, if they are not in the target audience of advertisers this is not going to work. Also, if visitors are experienced Internet users (using the internet all the time), they 'll be blind to ads and will no longer pay attention, then they will not click, and Adsense will consider that the profile of your visitors is not of enough quality for its advertisers.
Penalty can also come because of the nature of the content of your site(s).
- low quality content,
- clickbait,
- fake news,
- unhealthy related content,
- ...
