The platforms generally say your site shouldn't be more than ~1GB in size and less than some tens of thousands of files. This site in its nascency is about 15MB and <150 files. I don't plan to start posting RAW photo galleries, so if I start hitting those limits, please be concerned for my health and safety.
So why is Cloudflare Pages' bandwidth unlimited?
Why indeed. Strategically, Cloudflare offering unlimited bandwidth for small static sites like mine fits in with its other benevolent services like 1.1.1.1 (that domain lol) and free DDOS protection.
As a CDN provider, I believe it holds significant advantages in terms of traffic and bandwidth, such as economies of scale.
There's a repo on GitHub called awesome-cloudflare, which features a collection of open-source tools built on Cloudflare. It's truly fantastic.
Cloudflare is referred to as the "Cyber Bodhisattva", and I really like it.
Business design, for success and customer satisfaction!