What is a possible cause if an authenticated user is logged out when attempting to apply a coupon?

An authenticated user may be logged out when attempting to apply a coupon due to issues with the CSRF (Cross-Site Request Forgery) token validation. CSRF tokens are critical for ensuring that requests made by the user are legitimate and come from the authenticated session. When a CSRF token is not correctly validated, it can trigger security mechanisms that end the user session to protect against potential attacks. As a result, the user may find themselves logged out unexpectedly when they attempt to apply the coupon, as the application no longer recognizes their session as valid.

The session storage being configured incorrectly could lead to different issues, but it would not specifically cause a user to be logged out at the moment of attempting a coupon application. Using an outdated browser may affect the user experience or functionality but does not directly cause logout events related to CSRF validation. While an invalid coupon code can prevent a discount from being applied, it would not cause an authenticated user to be logged out, as that is unrelated to session management or authentication processes.