Cloudflare, a global leader in Internet networking and a backbone of the internet has had a downtime issue with its core API Services which run millions of websites.
The incident has been reported and a fix is being worked on.
The update of this can be tracked on https://www.cloudflarestatus.com/incidents/xvs51y9qs9dj
Many websites are experiencing 500 Internal Errors and 522 Errors due to this, which should be resolved soon.
Update:
As per the update, Cloudflare has already implemented a fix and are currently monitoring the service, their API services should be back online and functioning normally.