If you are using a display with non-100% scaling, pixels are captured as-is (which can be seen on the screenshots taken with 1/2 in General demo), but GameMaker games follow display scale, so the window grows larger.
- Manually flagging an application to not scale using Compatibility tab.
- Scaling back the drawn surfaces to account for DPI scale (I think you’d need an extension for getting the display scale factor)
- Marking the application as DPI-aware (most likely through manifest) - something to investigate.