The PC turns off when playing Roblox

I've been playing roblox for a long time, I used to play on a weak monoblock, now on a very powerful PC (for about 3.5 years now), but for the last 2 years roblox, after an average of 20 minutes, the PC just turns off, the monitor turns off in just 1 instant, the unit lights up and turns on for about 5 more seconds, after which it also turns off, when I turn it back on, Bluetooth usually doesn't work for about 2 minutes, as well as either the mouse or keyboard. What should I do about it? I tried reinstalling roblox, updating drivers, and writing to support, but they didn't respond. really important: This doesn't happen in any other games, I've played rdr 2, cyberpunk, GoW, and many other demanding games, but it's NEVER happened there, it's only in Roblox. None of my friends have ever had this before, but recently my friend's laptop also started shutting down, just like mine. Please help me.