I kept getting logged out of sites without doing anything. Tab would be open, I'd switch back to it, and the session was gone. It took me longer than I'd like to admit to connect the dots.
Chrome's Memory Saver (Performance settings) fully discards inactive tabs to free up RAM. Not just sleeps them. Discards. The page gets torn down. Any session state that lived only in memory is gone, and when you click the tab again Chrome reloads it from scratch.
Sites that rely on in-memory session storage (not cookies, not localStorage) lose that
state on discard. You come back to a freshly loaded page with no session. It looks exactly like
being signed out.
The fix: Go to chrome://settings/performance and either turn Memory
Saver off, or use the "Always keep these sites active" list to exempt the sites where it's causing
problems.
The broader takeaway: if users report random logouts on your site, ask whether they have Memory Saver enabled before assuming something's wrong with your auth implementation.