RAM is used quickly, and the MacBook freezes instantly

I’m using a MacBook PRO Early 2011, which I upgraded the RAM to iFixit 16GB RAM Kit, the issue which I’m having now, is that the RAM is consumed quickly, and the Mac freezes, only hard reset helps it. The problem appeared several weeks ago.

The Mac is used for react-native development, and it freezes, when iPhone simulator is turned on. Meanwhile there’s launched Chrome (I have maximum 10 tabs opened there), and Visual Studio Code. Having these apps launched I can achieve maximum of 2 GB RAM free, which randomly bounce between 16MB and said 2GB of free RAM. What can be the problem for such drastic RAM usage?