You haven't shown all of your code, but it looks like you are reading an array, then using a global hash to create the data from each row, then pushing the hashes to the existing array, but then you are only writing to JSON the most recent update to the global hash, and not the array. I think you need to do something like this (untested):

my @updated_data;

foreach my $result (@$result) {
    
    my ($id, $location, $name, $gender) = @$result;
     
    my %hash = ( "id" => $id, "location" => $location, "name" => $name
+, "gender" => $gender);
    push( @updated_data, \%hash );

}

my $json = encode_json \@updated_data;
print $CGI->header( -type => 'application/json' ),$json;
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