Blocked script execution in ‘about:blank’ – sandbox

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Blocked script execution in ‘about:blank’ because the document’s frame is sandboxed and the ‘allow-scripts’ permission is not set.

Huge quantity of client’s log …

Issue on CF side I guess, but not really usable as it is
https://community.cloudflare.com/t/blocked-script-execution-in-about-blank-because-the-documents-frame-is-sandboxed/813576