This behavior is a product limitation. The VMSP (VCF Management Platform) utilizes a rolling update process when DNS or NTP settings are modified at the VCF instance level. The platform restarts and recreates all internal service pods to apply the new configuration. The total duration of this task depends on the number of pods within the VMSP cluster.
Currently, no workaround exists to reduce the propagation time or bypass the rolling update in VCF 9.1.x