By default the refresh rate of the OLED panel effecticely bottoms out as 46hz, because as soon as you set your frame limit to 45, the screen will double it’s refresh rate to 90hz for half v-sync. How low can it go if you decouple the limiter from the refresh rate in the settings?
I have found repeatedly in all games if you don’t use the Steam Deck’s frame limiter and instead opt for in-game vsync, the latency drastically improves. Combine this with the RefreshRate Unlocker mod and a tweak that allows me to lower the Deck’s native refresh rate all the way down to 30hz, this makes playing games at 30hz suprisngly responsive and enjoyable for demanding titles.
According to the video reviews I’ve seen, there are many threshholds (40, 60 and 90 Hz) so it can effectively run at 20Hz if needed (though why you’d want to run that low is beyond me).