Computer Configuration > Administrative Templates > Microsoft Edge
Both
HKLM\Software\Policies\Microsoft\Edge
https://github.com/w3c/ServiceWorker/issues/765 asks srcdoc iframe with the "allow-same-origin" sandbox attribute to be under ServiceWorker control. By default (if left unset) or when set to Enabled, Microsoft Edge makes srcdoc iframes with "allow-same-origin" sandbox attributes to be under ServiceWorker control. Setting the policy to Disabled prevents ServiceWorker control over srcdoc iframes. This policy is temporary and planned for deprecation in 2026.