From what I’ve read, the RRC INACTIVE state is essentially similar to RRC IDLE, as there are no SRBs (Signaling Radio Bearers) between the gNB and the UE.
So, for the gNB to force the UE into RRC IDLE, it would first need to transition the UE back to RRC CONNECTED and then directly release it to RRC IDLE.
When RRC INACTIVE is enabled in the network, IDLE mode usage is almost negligible, as the UE remains in INACTIVE (provided the UE supports it) due to a longer inactivity timer compared to IDLE mode.
Additionally, based on my understanding, the UE can transition directly from INACTIVE to IDLE when required.
A UE cannot release an SCell on its own without a command from the network. Suppose a user with Carrier Aggregation (CA) enabled experiences inactivity triggers, and the network sends an RRC Release with suspend configuration. In this case, what happens to the SCell added at the UE’s end?
Alternatively, we can consider a different sequence: if inactivity triggers while CA is enabled, the network may first release the SCell before sending the RRC Release with suspend configuration.