We have been receiving reports recently that ads are appearing again on Crunchyroll.com after being blocked for several months. This site has apparently started using a very aggressive form of ad-block circumvention technology that is extremely difficult to block.
We have reported the ads to the filter list authors. (We don't maintain the filter lists ourselves.) Keep your filter lists up to date to make sure you get any new filter rules the list authors release. Please note, however, that there may be no way to block these ads now without also blocking the content you came to see.