Apps · App updates after a move
What is the Relocated apps watch?
Short answer: A background check that spots when an updater reinstalls a moved app on your Mac, waits until you quit it, then moves the new version back to your fast drive. See it in Settings → Services.
It's a quiet background check that keeps moved apps on your fast drive. If an app's updater (Adobe's or Microsoft's, for example) reinstalls a moved app in its original spot — which would silently fill your built-in drive again — the watch notices, waits until you quit the app, tidies up the old copy on the drive, and moves the fresh version across. You don't need to do anything.
You can see it in Settings → Services as Relocated apps watch, showing statuses such as Standing by, Watching N apps, Waiting for N apps to quit or N apps need your review.