I'm one of those people that uses DLSS, because I've got a large fancy 4k monitor that is big enough that is looks like shit at lower resolutions.
DLSS is better than nothing but it's no replacement for native rendering, it introduces a heap of visual anomalies and inconsistencies, especially in games with a consistent motion (racing games look like shit with DLSS), so I tend to be having lows of 50fps on medium before I'll even think about DLSS.
I'm also pretty sure Nvidia is paying devs to have it on by default, because everytime it's patched into a game they clear all the current graphics settings to turn on DLSS, at least in my experience.
I hate how AI upscaling looks and I really don't get why everyone seems to be gaga over it. In addition to the artifacts and other weirdness it can introduce, it just looks generally like someone smeared vaseline over the picture to me.
I've tried upscaling with ESRGAN as well and it has similar problems. It messes with the original textures too much. For example, it made carpet look like a solid surface. Skin looks too smooth and shiny. That kind of thing.
It depends a lot on the source picture, but it's definitely not a general problem inherent to AI upscaling. Otherwise there wouldn't be so many positive examples of ESRGAN.
This is a big part of why I'm sticking to 1440p for as long as it's a viable option. Not like my imperfect vision with glasses on would benefit from more PPI anyway.