This is absolutely not how it works. CDNs, and Cloudflare in particular, have lots and lots of IP addresses and don't share the same one with all the websites, instead they shard websites to IP addresses, so each website sticks to specific IP address. The reasoning behind this is usually all the legal risks, blocking risks, etc. For example, if some government wants to censor a website they are going to lookup its IP address and block it, if the website jumps across many IP addresses they may block all the subnets those addresses belong to, so they can cover all possibilities, which is going to censor lots of other websites on those subnets and make CDN pretty useless as a CDN.
Anyway, such approaches in combination with all the IP addresses of subresources each website links to can identify 95% of top 1 million websites, more than 95% if response sizes are taken into account. No amount of silly encryption toys like DoH, eSNI and TLS 1.3 can protect against it. You need some serious privacy technology to address the problem, like decentralized peer-to-peer overlay networks.
Anyway, such approaches in combination with all the IP addresses of subresources each website links to can identify 95% of top 1 million websites, more than 95% if response sizes are taken into account. No amount of silly encryption toys like DoH, eSNI and TLS 1.3 can protect against it. You need some serious privacy technology to address the problem, like decentralized peer-to-peer overlay networks.