Watched a full video, didn't really help much, all the extra settings are turned off aswellCan’t speak to your monitor specifically but I bought a gigabyte monitor that at first was similar to what you described. I basically went into custom mode on it and turned sharpness all the way down, or almost all the way down, any overclocking the monitor was doing I turned off etc. Basically you want to try turning off any extra processing the monitor is attempting to do.
You may take a look at this YouTube channel and see if he goes over a monitor similar to yours. I think I may have used something similar to this where they try to show ask the various settings.
https://youtube.com/@PCMonitors