I tested it and I have the special chars in the same way as expected readable. I think you uncompress the file on another machine or on a remote mounted filesystem where the charsets differ. IMHO this is not a zip problem.

#!/usr/bin/perl

use Archive::Zip qw( :ERROR_CODES :CONSTANTS );
my $zip    = Archive::Zip->new();
my $member = $zip->addDirectory('test/');
$member = $zip->addFile('test/straße.txt');
$member->desiredCompressionMethod(COMPRESSION_DEFLATED);
die 'write error' unless $zip->writeToFileNamed('someZip.zip') == AZ_O
+K;
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