"Tracker is installed by default with Ubuntu 19.04. Tracker is a filesystem indexer, metadata storage system and search tool"
So no real privacy issue here or anything. But load on the system may be annoying. Boloo should be the KDE equivalent and I don't like it.
PS: Yes, this stuff can be annoying: " It wasn't installed by default until now due to performance concerns, but those issues seem to have been resolved."