Cloudfront, by Amazon's own admission, specialises in high bandwidth delivery (ie huge videos). Fastly has consistently better performance as a small object cache, which makes it the choice for web assets

https://www.streamingmediablog.com/2020/05/fastly-amazon-hom...

Fastly gives them the edge performance they need without having to build it themselves. They have been a customer for a while I think.

Yeah, this is what makes me feel this is more an AWS thing