Updated to Sequoia, now crashing games close all apps and force a login

Just updated my MBP to Sequoia, and since then have been having real problems with playing games on Steam that worked fine before the update. A recurring theme is that the game will crash, all my applications close, and I have to log back in to my machine -- but notably, it is NOT powering down or rebooting, this is all happening within the space of a second or two What might be going on? Could this be a graphics driver problem?