Is it mandatory to set reestablishPDCP whenever Security Key is changed?
reestablishPDCP
Indicates that PDCP should be re-established. Network sets this to true whenever the security key used for this radio bearer changes. Key change could for example be due to termination point change for the bearer, reconfiguration with sync, resuming an RRC connection, or the first reconfiguration after reestablishment. It is also applicable for LTE procedures when NR PDCP is configured.