Sure, I'm fine with that. The problem is that I don't know how much it'll cost if I fall out of their free tier.
If I go with Bunny.net, I can get bandwidth for $0.005/GB (on their volume tier with 10 PoPs) or $0.01/GB (on their standard tier with 114 PoPs). $1,000 will buy me 200TB of bandwidth on their volume tier. If I'm using 200TB on Cloudflare, what is that going to cost me? $500? $10,000? Fastly's list price is $0.12/GB for the first 10TB + $0.08/GB after that so their price would be $16,400. And I'm sure that at 200TB/mo, I wouldn't be paying Fastly's list price, but at least I have an upper bound on the pricing. With Cloudflare, I really don't know.
> "use it and hope for the best, 'till you get a notification from CloudFlare"
I'd be fine with this if there were a 30-day migration window that I'd get (or something like that). The problem is that there have been a few stories of Cloudflare moving very quickly against a customer's usage.