I'm not 100% certain of anything, but I've never had any sort of Pc reboots since I've done the latest two NVIDIA drivers and playing The Veilguard.
(I did just clean the inside of my PC, got rid of any excess dust and whatnot, I considered it might be an overheating issue.)
There is a chance its a coincidence, and my PC is breaking down just as I started playing The Veilguard, but I'd rather it be a software and/or game issue rather then it be on my end, cause either fixing or buying a new PC can get expensive, not to mention time consuming.
I'll continue troubleshooting, and note any major changes in my main post.
(P.S I did play another session of Age of Wonders 4 and it didn't reboot on me.)