Description
What version of React Router are you using?
6.4.3
Steps to Reproduce
The ScrollRestoration component relies explicitly on the ambient window and document objects, but a router can be configured with a custom window, which means that the ambient one is unsuitable.
Mount an <iframe src> where the src has the same Origin as the global window, then mount a <ScrollRestoration /> inside of this iframe (you can mount the entire app inside the iframe; it doesn't matter).
Expected Behavior
When the iframe navigates, the scroll within the iframe is restored.
Actual Behavior
The parent window has it's scroll saved/restored by the ScrollRestoration, despite the component being mounted in a different window.
Note that this code changed recently with #9573 however the new implementation still relies on the ambient document, so even specifying an ID inside of the iframe would not resolve the issue.