Freeing up space · Local snapshots and held space
Why doesn't Storage Studio show how big each snapshot is?
Short answer: macOS reports only one combined size for all local snapshots, not per snapshot. Storage Studio shows that total honestly rather than inventing a split.
Because macOS doesn't report one. It gives a single combined figure for all local snapshots and no size for any individual snapshot. Storage Studio shows that combined total and says so, rather than dividing it up and presenting made-up numbers per snapshot.
What it can tell you for each snapshot is its age, when it was created, why it exists and what can be done about it. To free a specific amount regardless, use Custom reclaim.