To my knowledge, any cast is very much a thing cloudflare uses.. It allows to split traffic per region, which, in the case of DDOS is a good thing.

To be clear, they definitely use ingress anycast (ie anycast on external traffic coming into Cloudflare). The main question was whether they (meaningfully) used egress anycast (multiple Cloudflare servers in different regions using the same IP to make requests out to the internet).

Since you mentioned DDOS, I’m assuming you are talking about ingress anycast?