A friend of mine was nearly furious at suggestion that I can see the difference between native 4K and upscaled with DLSS - "No chance, I'm using it on 55" OLED, and there is NO DIFFERENCE!"
Then we established that he mainly games as he would on a gaming console - from comfortable distance to view the whole screen, playing fast paced shooters and role playing games mostly using controller, not keyboard and mouse. At his distance, even 1080p looked good, and by focusing on larger area of screen there's very little chance of noticing minor differences in image quality on small detail.
Then we compared it with my usage, 27" 4K screen at close distance, playing flight and racing sims where you are often focusing on small detail on screen, like target, runway, enemy, a curve in the far distance - you notice every small difference in Anti Aliasing, every drop in native resolution due to DLSS... It's similar with real time strategies and similar games with lots of small detail.
PC gaming is much more varied than console gaming. For my friend's usage, it mostly held true that even "performance DLSS" looked good.