COOP value is unrecognized
Cross-Origin-Opener-Policy is set to a value this scan does not treat as an isolating policy.
Why it matters
An unrecognized value may be ignored, which leaves the default shared context in place.
What to do
Use same-origin, same-origin-allow-popups, or restrict-properties.
Reference
COOP isolates the browsing context unless explicitly relaxed.