Please enlighten me

I have a question about a situation involving a website that appears to have been hijacked for the purpose of keyword ranking in gambling. When I search for high-traffic keywords, the site ranks well. However, when I access the site in desktop mode, it redirects me to the legitimate site, and the title displayed upon inspection matches the actual domain title. In contrast, when I switch to mobile mode, it redirects me to an AMP page, even though the original HTML contains no AMP links. Additionally, the title and meta description are different from those of the legitimate site. How is this possible?