I updated my macbook, ran the command, this is the output:
** Checking the container superblock.
Checking the checkpoint with transaction ID 3553472.
** Checking the EFI jumpstart record.
** Checking the space manager.
** Checking the space manager free queue trees.
** Checking the object map.
** Checking volume.
** Checking the APFS volume superblock.
The volume Macintosh HD - Data was formatted by newfs_apfs (945.200.84) and last modified by apfs_kext (1677.120.9).
** Checking the object map.
** Checking the snapshot metadata tree.
** Checking the snapshot metadata.
** Checking the extent ref tree.
** Checking the fsroot tree.
warning: apfs_fs_alloc_count is not valid (expected 13531069, actual 13531453)
Fix apfs_fs_alloc_count(oid 0x402, xid 0x3638c0)? NO
** Checking volume.
** Checking the APFS volume superblock.
The volume Preboot was formatted by newfs_apfs (748.30.60) and last modified by apfs_kext (1677.120.9).
** Checking the object map.
** Checking the snapshot metadata tree.
** Checking the snapshot metadata.
** Checking the extent ref tree.
** Checking the fsroot tree.
** Checking volume.
** Checking the APFS volume superblock.
The volume Recovery was formatted by newfs_apfs (748.30.60) and last modified by apfs_kext (1677.120.9).
** Checking the object map.
** Checking the snapshot metadata tree.
** Checking the snapshot metadata.
** Checking the extent ref tree.
** Checking the fsroot tree.
** Checking volume.
** Checking the APFS volume superblock.
The volume VM was formatted by apfs.util (945.250.134) and last modified by apfs_kext (1677.120.9).
** Checking the object map.
** Checking the snapshot metadata tree.
** Checking the snapshot metadata.
** Checking the extent ref tree.
** Checking the fsroot tree.
** Checking volume.
** Checking the APFS volume superblock.
The volume Macintosh HD was formatted by storagekitd (1677.81.1) and last modified by apfs_kext (1677.120.9).
** Checking the object map.
** Checking the snapshot metadata tree.
** Checking the snapshot metadata.
** Checking snapshot 1 of 1 (com.apple.os.update-F8CC686BD994CAC58E0A525C64B2C9D6329887202C9FA5AC86D15A7994507C67)
** Checking the extent ref tree.
** Checking the fsroot tree.
** Checking the file extent tree.
** Checking volume.
** Checking the APFS volume superblock.
The volume Update was formatted by com.apple.Mobile (1677.81.1) and last modified by apfs_kext (1677.120.9).
** Checking the object map.
** Checking the snapshot metadata tree.
** Checking the snapshot metadata.
** Checking the extent ref tree.
** Checking the fsroot tree.
** Verifying allocated space.
warning: overallocation detected on Main device: (0x2de9ddc+384) bitmap address (0x105ba)
Fix overallocation (0x2de9ddc+384) bitmap address (0x105ba)? NO
** The volume /dev/rdisk1 appears to be OK.
I don't know if it matters but my Macintosh HD APFS System Volume now says "System Snapshot Mounted" and is sort of grey.
Thanks for helping btw