Called when the panel has been dismissed from the system UI, either through user interaction or other events. This causes requestsRemoval to be set to true. The panel will be removed from its frontend, causing onRemovedFromFrontend to be called. This destroys the lifecycle and prevents the panel from being shown again.

This should only be called from components that already handled the dismissal process, such as a system UI that animated a panel away after a user swiped it away. For triggering the dismissal initially, dismiss should be used instead.