The complaint is that Cloudflare was not upfront about this limitation. They are clearly quite upfront. They more or less say exactly what the other commenter accuses them of not being upfront about.
> 1. It doesn’t help that the “percentage” is ambiguous
Would it have mattered? OP said they are using them as an image proxy; that's nearly 100% traffic served. Any way you interpret the word "disproportionate", running an image proxy will trigger.
> 2. A couple of days warning or suggestion to move to a higher paying plan would be nice instead of just shutting them down.
How they choose to handle an issue is also outlined upfront in their ToS. It's not really relevant in the context of this thread.
They may be an asshole, but they straight up told you, the other commenter, and OP exactly what they don't allow and what will happen.