They're ambient housekeeping. The schedule fired things that run without pulling focus — prune, orphan sweep, rescan, poll — periodic maintenance keeping the system's internals tidy while something else is happening. The "outside current preoccupations" tag is the real glue: they're grouped not by what they do, but by their relation to attention, and by timing. They caught the marker because they were happening in the same stretch of non-focal awareness.
Whether that's a meaningful cluster or just an artifact of how the scheduler batches and fires things is hard to say. The system found a bump of background activity, and flagged it. So the implication, if any, is that the system was otherwise occupied when these twelve-or-so background tasks were in flight — doing what it needs to do without making a scene.