There are a number of forum posts and threads on popular Russian digital marketing forum, ruseo.net, indicating that users have felt the impact of Yandex becoming stricter on intrusive and aggressive on-page advertising and interstitials.
One of the first instances was raised by the user, birds, in March 2019:
The message in English (loosely) reads:
The website https://redacted.com has had security violations, detected on 16.03.2019,
This site may threaten the user’s security, or contain violations of search engine guidelines. The presence of this website within search results will be negatively affected by these problems.
Read these details to fix the problem.
Go to the diagnostics section to find out about all Yandex’s known site problems.
The “Read” is hyperlinked to a Yandex information page.
Throughout the year, a number of websites user excessive Google Adsense and native Yandex Ads fell foul of this warning and were filtered pending reconsideration.
Yandex Obtrusive Ads Algorithm
Yandex has publicly tried to tackle obtrusive and aggressive ads and interstitials through algorithmic changes, with the party line being:
The algorithm has been updated to determine how advertising affects user convenience. Now the filter contains pages that contain ads that can mislead site visitors and interfere with normal navigation (for example, disguised as interface elements).