Windows 10, with Edge 20 but running under emulation on my Mac through Parallels. Screen res is the 5K screen and it is an SVG.
I tried re-setting the size down to it's original 728x424, making sure constrain proportion was clicked and then re-sized that element back up, but didn't make any difference.
It's definitely that background svg that's the issue as you can see that the little yellow circles (No's) aren't distorted and if you drag the window in on PC/Edge and another version kicks in at the breakpoint, it's background SVG is fine with no distortion.
Maybe I'll just convert the background to a PNG.