Nothing so complicated. The HTML source of femboy.ca/ literally contains:

    <img src="https:////ipv4.games/claim?name=femboy.cat" hidden>
However, the question is why would this domain get 20 million distinct visitors (before being posted on Hacker News)?

Interesting. I looked up top 10 domains. I wonder if you could have it occur on wikipedia.org? Other random thoughts after looking at https://radar.cloudflare.com/domains... Maybe tiktok somehow? Or a bug in NTP? :D