The hump – SEO WIKI
Nepot is a filter that Yandex search engine uses. It was introduced to deal with purchased links and sites that abuse link sales.
This filter reduces the influence of external links to the site, and the position decreases at the site where these links are located, but the acceptor site keeps the position in the search results. This allows you to improve search results, saving it from uninformative resources.
When a nepot filter is applied, the link weight either decreases or is completely zeroed. If such a filter is applied by the search engine, then you should change the links or remove them completely. In order to avoid its imposition, you should purchase links that look as natural as possible.