I've been having this issue for several months now and at first I assumed it was overheating. So I bought some new thermal paste and reapplied it but this didn't solve the shutdown issue.
I've tried to "re-create" the shutdown but nothing I do seems to be able to "cause" a shutdown. At any given moment on my PC I have 3 things running. Discord, an internet browser (Firefox or Brave), and sometimes a video game. I've been on my PC and have had all of these programs opened and closed in a variety of combinations and from what I can tell there doesn't seem to be any correlation. I use a dual monitor set-up with my main monitor where I have Discord or a game running, and I have my web browser open on the 2nd monitor usually on YouTube playing videos or music.
And it isn't consistent. Some days I'll have 0 shutdowns, other days I will get multiple shutdowns in the span of an hour. I ran a virus scan and nothing pings as a problem so I just don't know what to do.
For the record my GPU is an AMD Radeon RX 7600 and all drivers are up to date.