Cloudflare uses lava lamps as a source of randomness.

“Uh, you know, that's why Cloudflare has our lava lamps is so that, uh, uh, you can get good randomness. Uh, and when, uh, uh, a key out there is, uh, they use the seed, they use the initial, uh, uh, thing to, uh, uh, kind of create it, uh, with a single number four, uh, uh, it's, it's gonna be, uh, uh, reverse engineered.”