NTPD must be checking ownership matches the user that NTPD is running as, rather than attempt to write to the drift file.
As NTPD is run as root, it does have access to the drift file, regardless of the ownership on the drift file.
I’ve added to the patch file for v103 that sets root:root to the drift file.
I think we will not bring NTP back, as we just removed it completely from DietPi code for v6.9: https://github.com/Fourdee/DietPi/pull/1628
Systemd-TimeSyncd is enough in most cases an pre-installed on every Debian based image.
But it is most easy to do time sync via another application, aside from DietPi.
Go to DietPi-Config > Advanced Options > Time sync mode and choose “0 Disabled”.
Then install NTP via APT: apt install ntp
It will create a service that starts on boot automatically. DietPi cron job will not interfere then with this.
If NTP is already installed and adjusted by DietPi, it might be necessary to purge it once and reinstall it: apt purge ntp