I’m also having this same problem. At first I thought it was a problem with my computer. I ended up doing all the hardware tests but I couldn’t detect anything with a problem. Everything was normal. Temperature, memory clock, CPU, GPU and RAM usage, power supply voltage, nothing with a variation in the tests. However, when I’m playing Diablo, it crashes and my computer restarts after about 5 seconds with it frozen. The Windows log events show a critical alert saying that the system crashed and it ended up being shut down. Diablo 4 is the only game that has this problem. I’m 100% sure that this problem is with Diablo 4. You can rest assured with your computers.
Other games tested
*Rust
*Path of Exile
*Cyberpunk 2077
*Dota 2
*Warframe
*Middle-earth: Shadow of War
the problem persists in patch 2.0.3