My PC resets every time in the same dungeons

The issue is quite weird. Not sure if that’s relevant, but at about the same time I lost connection to ethernet (external issue) and now while I’m waiting I’m playing on my mobile data through tethering.

To the point, whenever I am a boss rush/sea of indolence/tranquil karkosa and occasionally at Aira pond (I was at literally at all abyssals four times this week and issue happens only in these dungeons) my PC will just randomly shut down and reset without any warning. I’m monitoring my temperatures but they all seem to be fine, I recently undusted the belly of my PC to see if it’s gonna help, but it didn’t. Doesn’t matter if I turned on the PC 20 minutes ago or 8 hours ago, the issue will repeat in the stated dungeons.
I’m at a loss of what could cause the issues as they were not present 2 weeks ago at all and it’s new for me.