Is the graph showing the number of requests served by HTTP/3, or the number of individual hosts that support it? I believe it's the former, and it's explainable

Is the graph showing the number of requests served by HTTP/3, or the number of individual hosts that support it? I believe it's the former, and it's explainable by the fact that most people these days visit only the same handful of siloes: Google, Amazon, Facebook, Twitter and Youtube probably make 90+% of all anonymised requests seen by Mozilla. But I doubt even 20% of global webservers are HTTP/2 ready, let alone HTTP/3. So HTTP/3 is eating the world, if by world you only count FAANG websites, which sadly seems to be the case. Remains to be seen how many websites are hidden behind tech's favorite MITM, Cloudflare, which might make figures a little harder to discern.