You might have a permanent or temporary redirect set on your site that directs users from Yandex search results to a third-party resource instead of your site.
If this kind of violation is found on your site, it was probably attacked and the redirect code was installed on it.
Yandex detected that I have this violation. How do I fix it?
Use the recommendations in How to protect your site from infection.
After you remove the violation, click the I fixed it button on the Security and violations page in Yandex.Webmaster. The restrictions are usually lifted within a month after you clear the violation. When the restrictions are lifted, the violation mark will disappear.
You can click the I fixed it button again for the same site after a month. Further, this period is increased up to three months to avoid the button misuse. Therefore, we recommend using the button only when you are sure that there are no more violations on the site.
If multiple users have website management rights in Yandex.Webmaster, agree on who will send the website for re-checking and when. After clicking the button, none of the users will be able to click it again within a month.