NeedforGapsInfoNR in R16

3GPP R16 introduced new IE NeedForGaps in RRCReconfigurationComplete & RRCResumeComplete messages. Here, UE need to provide measurement gap information {gap, no-gap} to the network against the target frequency bands sent by gNB.

My question is, how UE is determining which target frequency bands need gaps or no-gaps? Appreciate your help?

Also why gNB need this information from UE? Why gNB cannot determine by itself

NeedForGapsInfoNR
The IE NeedForGapsInfoNR indicates whether measurement gap is required for the UE to perform SSB based measurements on an NR target band while NR-DC or NE-DC is not configured.

TS 138 331 V16.4.1 https://www.etsi.org/deliver/etsi_ts/138300_138399/138331/16.04.01_60/ts_138331v160401p.pdf#page=481

That I know. I want to know, how UE determines whether gap is required or not for each target frequencies indicated by gNB ibn NeedFOrGapsConfigNR IE.