I'll be honest with you, on my TV, I can't tell the difference between 1080p and 2160p. I think it's because TV's have built-in upscalers while monitors don't. This is because the manufacturers know very well that there's almost no 4K content in the broadcast market and at the sizes that these TVs are (50"-70"), 1080p would look awfully grainy. I had been scratching my head about why I couldn't see any difference between 1080p, 1440p and 2160p when running the Far Cry 5 benchmark and that made me worried about my eyesight so I did a little digging.Good tips, especially for those using TVs.
I wonder sometimes about the push for 4k on consoles. High refresh rate and VRR displays are more impactful imo.