Google Admob does not show ads, but requests go. What is the problem and how to solve it?

Question

Google AdMob

For two months, ads in the application were shown well. But then I noticed that the impressions stopped, and the requests continued to go. There were 1,350 ad requests in the last week, but only 20 impressions. There are no account restrictions. Is it possible to determine what the problem is? And how to solve it?

Answer 1

or there is no advertising for the audience
or the sanctions were still there and removed (unlikely)
or something needs to be changed in the code