I have site that quickly went up to page 4 and 5 for most keywords. After using many PBN links the rankings seem to no longer move. Its as if the site it stuck on page 4 and 5 and wont move down or up. Most of these links are continually being placed. Most of the links are being indexed on ahrefs as they are built. Is there any explanation as to why a site would not move? The site is about 8 months old.