Yes, Cloudflare’s Under Attack Mode (IUAM) can block or degrade Google crawling and testing. Use it only during active attacks, keep it short-lived, and scope it to targeted paths if possible. To reduce impact, allow Verified Bots in Cloudflare, and consider explicit allow rules for confirmed Googlebot IPs.
I’ve tested this scenario: with IUAM enabled, Google’s tools were impeded. Rich Results Test reported that the URL isn’t available on Google, and Search Console’s URL Inspection failed to fetch, showing it was unable to access the page. This happens because the tools don’t reliably pass Cloudflare’s browser checks.
Cloudflare’s Under Attack Mode (IUAM) is an emergency feature that places a JavaScript challenge in front of requests to weed out malicious Layer 7 traffic.
While other CDNs have similar “under attack” modes, this explanation refers specifically to Cloudflare’s feature.
