How to determine the reason for the low depth of views?

Question

Yandex.Metrica

Hello! Since yesterday, my traffic has increased dramatically from 12 to 15 thousand visitors per day, and the depth of views has decreased from 13 to 9 per visitor.
In the metric, I determined what influenced this: devices "smartphone" + source "direct hits".
I compared this data with the parameters: devices "smartphone" + source "search engines".
And I got that from search engines, the depth of views from a smartphone is 7.5 pages. And for smartphones with direct visits, only 1.4. It just started yesterday. So far everything has been pretty much the same
. Can't decide what to check next and how to find the reason for such a rapid dew of direct hits from a smartphone and why there are so few views per visitor for them.
Plz kick in the right direction, where to look, what to pay attention to, because general behavioral factors suffer (viewing depth)

Answer 1

Webvizor in Yandex by use. You may notice something is wrong. Put yourself in the shoes of a visitor

Answer 2

Welcome to the club, read articles on the topic "Webmasters in RuNet note a massive invasion of bots."
On average, these bots look at the site for 20 seconds and exit. They completely destroy analytics by traffic sources in Yandex.Metrica.