please dont be panic. i also have galaxy note 9 exynos 6gb version. After the new updates of pubg mobile game,it seems hot and slowdown issue while gaming. same issue found my colleague who owns iphone xs max. so what i am saying is these hangup...slow...hot are also came due to the bud of games. so make sure the game you playing is stable and run smoothly in others end. keep upgrade your device to the latest Samsung update and uninstall unwanted junk apps. use only needed features of note 9. set your mobile to restart once in a month through device care. All the best!