You need to change that foreach to be keys %dateparts. As it is, it's going over both the keys and the values, and when it gets to value, it's false because that key doesn't exist yet.

foreach my $element (keys %dateparts) { ... }
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local $_ = "0A72656B636148206C72655020726568746F6E41207473754A";
while(s/..$//) { print chr(hex($&)) }
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