Weird. Which OS and drivers? Does it fix itself if you resize the window? You can try toggling full-screen with Alt + Enter and see if that does anything.
Mainly interested in the GPU and GPU driver version. You can get the driver information through AMD/nVidia's settings apps. Also good to know if you're using any tweak tools. Resetting drivers settings to default might help.
The game defaults to OpenGL rendering but you can force Vulkan from the commandline with:
MawManor_1_0_2.exe --rendering-method forward_plus
Your nVidia driver is a year out of date. The latest version is currently 566.03. I'd suggest installing updated drivers, and possibly checking the "clean installation" box (but keep in mind that this will reset any driver settings you've changed).
If you're looking for a good, no-bloat way to install the drivers, I recommend NVCleanInstall: https://www.techpowerup.com/download/techpowerup-nvcleanstall/
Does forcing the Vulkan renderer work for you? May also try changing the "OpenGL/Vulkan presentation method" in the nVidia driver settings.