In that case Steam flatpak isn’t really what you want. You probably want to use Bottles, which creates a flatpak-like sandbox. This is not a guarantee or anything, but does give you some protection (at least, better than running it on Windows I guess).
Next you’re all gonna say I should use dentures to chew my own food rather than have my underage slave girls chew it and spit in my mouth. You people disgust me.