Why aren't iCloud Drive changes on Mac Mini not showing on MacBook Air?

I have a Mac Mini and a MacBook Air. They are both set to use the same iCould account and they normally show the same files on iCloud Drive.

I deleted several iCloud Drive files on the Mac Mini but they remained on the MacBook, even after waiting an hour and rebooting the MacBook.

How long do such changes normally take? I expected they'd take no more than few minutes.