with any code which has:

use Win32::Unicode;
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inside it. So for example with your code:

use utf8;
use Win32::Unicode;

# unicode console out
printW "I \x{2665} Perl";

$from=poesía;
$to=canción;

# moveW $from, $to or die $!;
renameW $from, $to or die $!;
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I get:

I ♥ PerlUndefined subroutine &Errno::ERROR_FILE_EXISTS called at
+ C:/Perl/site/lib/Win32/Unicode/Error.pm line 31.
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Which version of Win32::Unicode do you have?

Despite your unquoted strings, it works for me

use utf8;
use Win32::Unicode;

# unicode console out
printW "I \x{2665} Perl";

$from='poesía';
$to='canción';

# moveW $from, $to or die $!;
touchW $from or die $!;
renameW $from, $to or die $!;
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