Interestingly this seemed to only affect resolver service. I use Cloudflare pretty extensively on all my sites, but only in DNS mode (no CDN / proxy). The hosts continued to resolve fine during the outage (following root DNS resolution chain, no recursive resolver involved). I imagine their CDN internally uses their resolver service which explains the outages, and some unrelated 3rd parties who don't use CF on their domain at all still created a hard dependency on CF by using their recursive DNS server.