Please remember that Cloudflare runs very strict and secure HTTPS. Thus, to use HTTPS tracker, both your operating system and client must be fully able to use TLSv1.2 (not 1.1 or 1.0) crypto. This is not a problem for anything running on Unix (and similar). But also, for example, (a completely up-to-date) Windows 7 x64 running uTorrent 2.2.1 still qualifies. Make sure your end is up-to-date before complaining. At any point you're welcome to simply use HTTP tracker. Paradoxically, security implications are minimal.