Major search engines redirect an HTTP link to a scammy pharmacy site

There is an HTTP website (not HTTPS) that works perfectly fine when the URL is directly typed into the address bar or when links are clicked from other websites/applications like Reddit, Facebook, and Discord.

The exceptions are the major search engines: Google, Yahoo, and Bing. When clicked from one of these sites, it is redirected to a scammy pharmacy site with one of many different domain names. This occurs in Chrome, Firefox, and Edge; it also occurs on Android smartphones. (Bing only does this in Chrome; it works fine in Firefox and Edge.) This issue occurs for multiple people on many different devices.

Interestingly, other search engines (Dogpile, Baidu, Ask, DuckDuckGo, Yandex, etc.) seem to work fine.

What could be the cause of this behavior? Do the search engines or the website need to be fixed, and how? Would converting to HTTPS help, and why?

The website in question is bluefurok.com. I am not the webmaster, but as a programmer and web developer I am curious about this issue.