It's your monitors resolution, specifically it's your Canvas Size and Output resolution. 1366x768 is not a capture friendly resolution. If you look at your Output resolution it says 1364x768.
1366x768 is not a 16:9 aspect ratio(technically neither is 1364x768, 1360x768 is the 16:9 resolution), OBS is scaling you 2 pixels horizontally which destroys the final output, distorting the image and colors.
You will have to sacrifice scaling somewhere to get it to output correctly, you want to be running 1280x720 Canvas and Output. This will cut off some pixels of your display capture, I wouldn't "Fit to Screen" but simply Center the source because you will run into the same issue with scaling if you try to fit it to the canvas.
TLDR; You cannot scale 1366x768 correctly, any attempts to scale it to a 16:9 resolution will cause shit results, don't buy monitors/laptops that run at 1366x768.
