Cloudflare has resolved the issue and services have resumed normal operation.
Posted Jul 29, 2020 - 23:48 UTC
Update
Cloudflare continues the roll out of the patch for this issue.
Posted Jul 29, 2020 - 20:51 UTC
Monitoring
Cloudflare is monitoring the phased deployment of a patch for this issue.
Posted Jul 29, 2020 - 19:00 UTC
Investigating
Some Cloudflare branded error pages (1xxx and 5xx) are currently being displayed without styling. Functionality is unaffected. Blocks, Challenges, CAPTCHAs, and Custom Error Pages are all functioning correctly.