## The problem
Issue firebase/firebase-js-sdk#3004 (closed, 50 comments): Firebase Auth logins stopped working for users browsing in Chrome incognito mode (SDK 7.13.1). No code changes on the app side; users just could not log in anymore.
## The fix
Community-confirmed fix: turn on third-party cookies for the incognito session. Commenter andrewhamili reports that flipping the third-party cookie setting on in incognito resolves it. Firebase Auth depends on third-party cookies for the session flow, and Chrome's incognito defaults block them, so users who hit a dead login in private browsing should check that setting before anything else.
## Notes
Thread: https://github.com/firebase/firebase-js-sdk/issues/3004. Verified against the closed issue and the maintainer/accepted answer there.