Yeah, or the manufacturer didn't use an updated iso to begin with. That happens.
Unfortunately you will not be able to switch out of S mode once you switch out of it.
To be completely honest with you, S mode is a nuisance. It is not allowing you to download anything outside of the store app. So if you need to run an installer for a printer driver, or install OEM driver directly if you ever need to, it will not allow you. It is ideal for computers used by kids or senior who are not tech savvy at all, as such restriction can prevent them from downloading something bad.
Once you switch out of S mode, and if you want to restrict yourself to download from store app only, you can go to Settings > Apps > Advanced App Settings. For "Choose where to get apps", set to the store app option. This way it will do what S mode does, except in S mode, you will not see this settings option at all to even switch out.