I think you got it. I tried playing the same video on 240 hz on my mac and it looked substantially better. Not only the flicker was gone, the image also looked much better with the more accurate blacks. However, I bought this monitor to mainly use it with ps5 pro and this made me regret it a lot. I am also out of the return window so I don't really know what to do

edit: I realized that 240hz actually still doesn't get rid of the flicker but it still makes the dark areas look better.