To add to this, DLSS 2 functions exactly the same as a non-ML temporal upscaler does: it blends pixels from the previous frame with pixels from the current frame.

The ML part of DLSS is that the blend weights are determined by a neural net, rather than handwritten heuristics.

DLSS 1 _did_ try and and use neural networks to predict the new (upscaled) pixels outright, which went really poorly for a variety of reasons I don't feel like getting into, hence why they abandoned that approach.