https://unix.stackexchange.com/questions/348850/why-df-and-finder-shows-different-available-disk-space

// The exact disk usage can be found in Apple Icon > About This Mac > Storage
// but, df or Command-i do not work well.

$ sudo tmutil listlocalsnapshots /
Password:
Snapshots for volume group containing disk /:
com.apple.TimeMachine.2019-11-01-133502.local
com.apple.TimeMachine.2019-11-01-213546.local
com.apple.TimeMachine.2019-11-01-232530.local
$ sudo tmutil deletelocalsnapshots /
Deleted 3 Time Machine local snapshots for volume group containing disk '/'
com.apple.TimeMachine.2019-11-01-232530.local
com.apple.TimeMachine.2019-11-01-133502.local
com.apple.TimeMachine.2019-11-01-213546.local