The match runs to completion before the map even starts.

At the time your map runs, $1 and $2 are what they are at the end of the global match.

Most likely you want pairs from List::Util:

 foreach my $pair ( pairs /(\d+)\s+(\S+)/mg ) {
       my ( $key, $value ) = @$pair;
       ...
    }
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... or a while loop:

    $h{ $1 } = $2
        while /(\d+)\s+(\S+)/mg;
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