Your Scanners See a Different Internet Than Your Users Do
A few years ago, cloaking was mostly a black hat SEO problem. Someone would serve one version of a page to Googlebot and another to human visitors, and the worst outcome was a spammy search result. It has since become one of the more effective evasion techniques in the phishing and malvertising toolkit, and most security teams are still measuring their external exposure from a vantage point that attackers stopped caring about some time ago.