Gaming Desktops

When I open games - specifically games, my computer restarts. This started ~2 days ago. I just downloaded and was playing Forza Horizons 5 Standard Edition. In the middle of a cut scene, I black-screened. I thought it was part of the game, so I sat there. After a few minutes, I decided I didn't want to play anymore so I tried to exit the game. I then realized that I couldn't. I couldn't ALT + TAB, access the WIN key to shut it down/restart, etc. I have a physical button on my computer to turn it off, so I went with that. I then left my computer off. A few hours later, I came back and turned my computer on. Since then, every game that I open causes my monitor to black-screen and reset to the default windows login screen. Applications, like Bing, GeForce Experience, NVIDIA Control Center, Settings, File Explorer, etc. all work fine. It is actual games that cause the black screen. My keyboard and mouse also restart. Inside my computer, however, the lights do not change/turn off like it would during a normal restart. I've contacted Microsoft, NVIDIA, gone through blogs online, etc. and nothing works. All of my drivers are up to date, I don't have any pending updates/option updates, and my computer is only about 2 years old, so I highly doubt it is overclocking, overheating, or something else like that. My warranty is expired, and this is really my last free option. This has never happened to me before, and I have no idea how to proceed. I can provide additional details if needed. Thanks so much for any help you can provide. Also, I am barely a tech person so providing details on how I should go about this would be much appreciated.