Issue when opening Planner via browser

Users are encountering a recurring sign-in issue when accessing Microsoft Planner directly through its URL, https://planner.cloud.microsoft. After signing in, closing the browser, and reopening Planner, they are prompted to sign in again. This occurs because no authentication information is being stored in the browser's cookies when using the direct link. However, accessing Planner through the Microsoft 365 apps portal does correctly establish authentication and store cookies. The user is asking if others have experienced this problem or if it's a known issue.