COOP
Making your website "cross-origin isolated" using COOP and COEP | Articles | web.dev
Some web APIs increase the risk of side-channel attacks like Spectre. To mitigate that risk, browsers offer an opt-in-based isolated environment called cross-origin isolated. Use COOP and COEP to set up such an environment and enable powerful features like `SharedArrayBuffer`, `performance.measureUserAgentSpecificMemory()` or high resolution timer with better precision.
https://web.dev/articles/coop-coep
Cross-Origin-Opener-Policy - HTTP | MDN
The HTTP Cross-Origin-Opener-Policy (COOP) response header allows you to ensure a top-level document does not share a browsing context group with cross-origin documents.
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cross-Origin-Opener-Policy


Seonglae Cho