Please let Perl help you and add the following two lines to the top of your script:

use strict;
use warnings;
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With that, Perl will tell you that you are trying to use a variable named 2023-01-01, which isn't really allowed in your current configuration of strict.

Most likely, you wanted to print a value from %HoH:

print $HoH{"2023-01-01"}{"00:00"};  #I couldn't see the value
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