u/CuteBench3226

I have been using the S21 Ultra for more than 3 years, and during this entire period I noticed that the device has never been able to exceed 8GB of RAM usage, even though it comes with 12GB of RAM. Once the usage reaches 8GB, the phone becomes extremely slow, and sometimes it automatically closes all apps. In other words, it becomes almost unusable as soon as it reaches 8GB of RAM usage. So what is the purpose of the remaining 4GB of RAM?