macOS uses snapshots to keep changes around in case you need to restore files. Disk utility can show you the space needed for each snapshot and delete them before the scheduled time when needed.

You did fine by waiting, but if you need to get the space sooner, you can manage that now you know this is intentional and the name of the app to show you snapshots.

• https://support.apple.com/guide/disk-utility/view-apfs-snapshots-dskuf82354dc/mac
• https://eclecticlight.co/2021/11/13/understanding-snapshot-data-in-disk-utility/
• https://eclecticlight.co/2021/11/09/disk-utility-now-has-full-features-for-managing-snapshots/

Pay attention to the tidemarks and Private Size:

Private Size is the size of the data only referenced by that snapshot, and is broadly similar to the amount of space which would be recovered if that snapshot were to be deleted.

macOS uses snapshots to keep changes around in case you need to restore files. Disk utility can show you the space needed for each snapshot and delete them before the scheduled time when needed.

You did fine by waiting, but if you need to get the space sooner, you can manage that now you know this is intentional and the name of the app to show you snapshots.

• https://support.apple.com/guide/disk-utility/view-apfs-snapshots-dskuf82354dc/mac
• https://eclecticlight.co/2021/11/13/understanding-snapshot-data-in-disk-utility/
• https://eclecticlight.co/2021/11/09/disk-utility-now-has-full-features-for-managing-snapshots/

Pay attention to the tidemarks and Private Size:

Private Size is the size of the data only referenced by that snapshot, and is broadly similar to the amount of space which would be recovered if that snapshot were to be deleted.

In your case the GB of data would be tied up in snapshots of disk1s1 and reviewable also from the command line:

diskutil apfs listSnapshots disk1s1