After leaving kubo running (with internet routable IP Address,), for approx 3 weeks, my datastore had grown to almost 40GB. After pausing and restaring the daemon, that shrunk to much more friendly 2GB.
Did restarting the daemon dump the DHT data I was holding? I was expecting those records to persist across restarts for the duration of their TTL.
If, on the other hand, I really only needed 2GB of disk space, I think kubo needs a way to trigger database optimization while in operation. (Or someone can point out the obvious part of the manual I missed.)