(info "(coreutils) Sorting the output") says
‘-r’
‘--reverse’
Reverse whatever the sorting method is—e.g., list files in reverse
alphabetical order, youngest first, smallest first, or whatever.OK but mention 'whatever' doesn't mean -U, -f, because they are sorted in "unsorted" order. In fact perhaps trigger an error. Actually directory order is still an order, so in fact it is odd that -r is "broken" here.
