A couple of reasons:

- The free CDN is basically unusable with my ISP Telekom Germany due to a long-running and well documented peering dispute. This is not necessarily an issue with Cloudflare itself, but means that I have to pay for the Pro plan for every domain if I want to have a functioning site in my home country. The $25 per domain / project add up.

- Cloudflare recently had repeated, long outages that took down my projects for hours at a time.

- Their database offering (D1) had some unpredictable latency spikes that I never managed to fully track down.

- As a European, I'm trying to minimize the money I spent on US cloud services and am actively looking for European alternatives.