https://hothardware.com/news/nvidia-dispels-dlss-myths-addresses-amd-criticism-gamer-questions
There is also an inherent weakness when working with lower resolutions. At 4K, DLSS has around 3.5-5.5 million pixels to generate the final frame, versus only 1-1.5 million pixels for 1080p. Having fewer pixels presents a bigger challenge for DLSS, hence why images look blurry.
We have seen the screenshots and are listening to the community’s feedback about DLSS at lower resolutions, and are focusing on it as a top priority. We are adding more training data and some new techniques to improve quality, and will continue to train the deep neural network so that it improves over time