I crated a separate topic because I thought my issue was different, but it seems more and more like this one as I find out more.
I can take that down and move the information here if that’s the thing to do. For now I’ll give a summary of my corroboration of the issue.
I’m on Fedora 40, which uses btrfs. I haven’t used any other operating systems on the device. After opening the computer from suspend, less than 20 seconds after login (and interacting with the previously open applications as usual), it goes black and shows the splash screen and login page anew. This doesn’t happen every time. My working theory is that it happens after the first suspend-open since the computer was last fully restarted or shut down, and doesn’t occur on subsequent suspend-opens on the same session. I haven’t done it enough to confirm.