Search engine ranking is up to the discretion of search engines. Whether your site comes up as a top search result depends on the search query and how relevant the search engine believes your site is to that query. It doesn’t necessarily indicate a security problem with your site, even a site that’s safe can still be ranked poorly.
If you’re concerned about search engine rankings, you may want to get a custom domain though. Free subdomains unfortunately have a poor reputation, and may make it a lot harder to rank in search engines.