COOP will process-isolate your document and potential attackers can't access to your global object if they were opening it in a popup, preventing a set of cross-origin attacks dubbed XS-Leaks.
The root cause of most XS-Leaks is inherent to the design of the web. Oftentimes applications are vulnerable to some cross-site information leaks without having done anything wrong. It is challenging to fix the root cause of XS-Leaks at the browser level because in many cases doing so would break existing websites. For this reason, browsers are now implementing various Defense Mechanisms to overcome these difficulties. Many of these defenses require websites to opt in to a more restrictive security model, usually through the use of certain HTTP headers (e.g. Cross-Origin-Opener-Policy: same-origin), which often must be combined to achieve the desired outcome.
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cross-Origin-Embedder-Policy
https://http.dev/cross-origin-embedder-policy
https://http.dev/cross-origin-opener-policy
https://udn.realityripple.com/docs/Web/HTTP/Headers/Cross-Origin-Opener-Policy
COOP will process-isolate your document and potential attackers can't access to your global object if they were opening it in a popup, preventing a set of cross-origin attacks dubbed XS-Leaks.
The root cause of most XS-Leaks is inherent to the design of the web. Oftentimes applications are vulnerable to some cross-site information leaks without having done anything wrong. It is challenging to fix the root cause of XS-Leaks at the browser level because in many cases doing so would break existing websites. For this reason, browsers are now implementing various Defense Mechanisms to overcome these difficulties. Many of these defenses require websites to opt in to a more restrictive security model, usually through the use of certain HTTP headers (e.g. Cross-Origin-Opener-Policy: same-origin), which often must be combined to achieve the desired outcome.