I'm having trouble with corners when playing a video full screen

As you can see from the attached screenshot, the corners are white in full screen (grey in dark mode), is there any way to turn this off?

Screenshot 1 is from Microsoft Edge 115.0.1843.0 dev
Screenshot 2 is from Microsoft Edge 113.0.1774.42

The screenshots were taken on YouTube, but we've seen the same issue on other video platforms (twitch, etc.)