Where to find the reason for the decrease in income?

Question

Yandex

I ran into a problem - the income from the mobile RTB block is falling. In the statistics, all parameters related to the cost of a click, the number of clicks, etc. are available only for direct blocks and I can’t find the reason for the drop in income and find out how I can increase it back.
How can you solve this?
Below is a graph that shows all available metrics that do not display revenue and total revenue per block. Only income falls.