[celsoazevedo]

I don't think it's that. OP seems to have a CMS (LucentCMS) and some sites using it (eg: kritikos-sm.gr) load images from a sub domain (eg: images.lucentcms.com).

While the CMS website receive normal visits and serves HTML content, for Cloudflare it's being used mostly to serve images, breaking their ToS. If the customer website was behind Cloudflare and they used their own (sub)domain to serve images they'd probably be fine because that domain would be serving a healthy mix of HTML and media content.

I think both OP and Cloudflare are in the wrong here. OP was using the wrong product for this and Cloudflare didn't give him time to fix the problem, losing a customer in the process.