Question: What happens when a MUSIM UE stops fulfilling the condition to be considered a MUSIM UE and has previously negotiated support of one or more MUSIM features?
Option 1: The UE continues to use the previously negotiated MUSIM features.
Option 2: The UE initiates a normal tracking area update procedure to indicate that all the MUSIM features are not supported.
Option 3: The network automatically revokes the support of MUSIM features for the UE.
Option 4: The UE is barred from accessing the network.
Explanation: According to the text, when a UE stops fulfilling the condition to be considered a MUSIM UE and has previously negotiated support of one or more MUSIM features, the UE shall initiate a normal tracking area update procedure to indicate that all the MUSIM features are not supported. This ensures that the network is aware of the change in the UE's status and can take necessary actions accordingly.