Freeing up space · Where your space went
What does "held in automatic backups" mean in Storage Studio?
Short answer: It's space your Mac's own local snapshots are holding for files you've already moved or deleted. The files are gone; the room comes back by itself, usually within a day, or via Release that space.
It's room taken by your Mac's own recent backup copies (local snapshots) of files you've already moved or deleted. The files really are gone; the space just hasn't been handed back yet.
In the space breakdown it's a line of its own whenever your Mac is holding anything, with a Release that space action beside it — the one thing that actually helps when deleting files hasn't. It usually returns by itself within about a day.
See what Release that space does and why deleting doesn't always free space.