Ctrl + 0 leaves a black border when in full screen mode

This behavior only started a few days ago. Maybe I accidentally changed some setting?

Case in point: My monitor is 1920x1080 and I open a document with the same dimensions. Ctrl + 0 should give the same result as ctrl + 1 and in fact did until a few days ago. The same thing happens no matter what the image dimensions or aspect ratio are. The edges of the image never touch the edge of the screen. There's always a black border.

See the attached screenshot for reference. It's a 1920x1080 document with the default white background in fullscreen mode.

To be clear, I'm pressing the 'f' key twice to enter full screen mode then pressing ctrl + 0

I'm on windows 10 and using the latest version of Photoshop (21.2).

I tried reseting preferences and updating Photoshop.

I saw another post where the person had an issue with a second monitor causing problems. I don't have a second monitor.