It bears mentioning that production on DK Bananza and Mario Kart World was well underway by the time they were moved from Switch 1 to Switch 2, (both started in 2017 but were shifted to next gen in 2020/2021) so a lot of their core technology was probably already in place, hence them mostly sticking with Switch 1 level rendering techniques.
Nintendo has also been making games at a similar level of technological advancement (Wii U/Switch 1) for well over a decade, and they use their own in-house technology, so their internal tools probably weren't overhauled to take advantage of Switch 2's capabilities in time for games like these to really benefit from it.
We'll see how things progress once titles that were designed from the ground up for Switch 2 start to come down the pipe.
