The two shifts are rather OS dependent and may cause a little grief if the code is run in a root directory. The code isn't very tolerant of foibles like unfortunately named files or directories - especially if they sort higher than the directories of interest.

Your while loop could be turned into a for loop:

my $start = ($highest / 1000) + 1;

mkdir "object${_}000" for $start .. $start + 9;
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