My first intuition is that this might be some kind of auto-detection from macOS, maybe originally intended for full-screen games. It's worth testing whether this also happens when we use native macOS fullscreen for video, with the pref `full-screen-api.macos-native-full-screen`. I don't see any mentions of this behavior in the Big Sur AppKit release notes, so we may need to contact Apple to ask whether it's possible to disable this.
Bug 1677266 Comment 1 Edit History
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My first intuition is that this might be some kind of auto-detection from macOS, maybe originally intended for full-screen games. It's worth testing whether this also happens when we use native macOS fullscreen for video, with the pref `full-screen-api.macos-native-full-screen`. I don't see any mentions of this behavior in the [Big Sur AppKit release notes](https://developer.apple.com/documentation/macos-release-notes/appkit-release-notes-for-macos-11), so we may need to contact Apple to ask whether it's possible to disable this.