The S2’s hygrometer is defective which I noted in my bakeoff between that and the Creality Space PI posted in a link above. Put simply, you can’t go by that. All this BS that one sees on the web is just that, BS, the measurements while true don’t amount to any material difference in drying. The thing will still dry even if the chamber is saturated with moisture. Don’t believe me, read my review and use the testing methodology I used and see it for yourself.
However, don’t fall into the trap that so many folks fall into when it comes to tech. This phenomena is often called “Spec Blindness” where people think that the numbers and details about a product, like a printer or computer, are the only things that matter. They mistakenly fall into the trap that marketers hope for and believe that specific numbers always mean better performance, without considering how the product actually works in real life. Filament dryers are arguably among the worst at praying upon consumers with fake “specmanship” and pretty “blinky” lights and fancy displays.
Note: In the case of a dryer, it is important to remember that Bambu X1 as an example, has a an effective bed dryer mode and do you see any controls that are tied to RH% do you? That is because anything heated up beyond ambient temperature will radiate moisture and if given enough time will dry out as anyone who’s left anything in car in the hot sun knows.
When I tested the S2, it was “adequate” in drying. I felt Sunlu misrepresented their product, so I returned it and kept the Creality Space PI dryer, which performed closer to its specs. Not that Creality were saints by any stretch of the imagination, they also exaggerated their specs, but not as much as Sunlu did.