Cloudfare does have a free CDN tier "For individuals with a personal website and anyone who wants to explore Cloudflare." but it's not the same as B2 including a CDN for free, even Azure is apart of the bandwidth alliance.
Right, but it means you can basically (ab?)use Cloudflare to get free egress from B2 storage. Cloudflare won't get too mad until you start hitting terabytes per month; even the free tier doesn't have restrictions.
You can also turn on an extremely aggressive caching policy with a page rule that will keep everything under a given subdomain for a month. This makes the "free CDN" part easy, though again, people who do this run the risk of getting their accounts terminated.
