Not even that. I have both Apple and non-Apple monitors, and my Mac only rounds the top edges on the MacBook’s screen, as intended.
Not sure what this tool’s function is supposed to be, given that the rounded corners only appear on screens that are actually rounded. Why would you want to straighten that out on a physically-rounded screen?
It’s more than that, the screen is rounded at the hardware level, there are no pixels to show anything here. What the OP software is supposed to “fix” CANNOT be fixed!
Not sure what this tool’s function is supposed to be, given that the rounded corners only appear on screens that are actually rounded. Why would you want to straighten that out on a physically-rounded screen?