Yes, there was some debating about restoring the cache. The main problem was determining how old the saved cache was. On a reboot - you know it’s fairly fresh. On the other hand, if you power off the router, reconfigure something, spend a few hours futzing around - on a fresh start - the cache could be quite old.
I wrote a script to timestamp the cache file on evey ubound-control dump-cache (via cron every 10 mins).
On a services-start if the time stamped cache was older than 30 mins, no reload.
I don’t recall now how
@Martineau implemented it in unbound-manager. I did this script before it was added.