Cubase can be a bit quirky like that, I had a problem with it flickering on a G-Sync screen because of the fluctuations. Luckily you can fix the frame rate and such things within the NVidia control panel, i.e.:
I think the main problem is that Cubase has been updated across decades to match modern hardware. Whereas newer DAWs are built from the ground up on newer frameworks and concepts that never existed for Steinberg previously.