Without regard to the correctness or fitness of your code for your purpose, there is scope for a little tidying up. Consider:

#!/usr/bin/perl

use strict;
use warnings;
use OSM::osm;

my @fieldNames = qw(name amenity operator vending);
openOsmFile($file);

do {
    my ($id, $lon, $lat, $nodeUser, $ref1) = getNode2();
    
    last if ! defined $id;

    my %fields;

    $fields{$_->[0]} = scalar $_->[1] for @$ref1;
    next if !grep {exists $fields{$_}} @fieldNames;
    print join ('^', $id, $lat, $lon, @fields{@fieldNames}), "\n";
} while (1);

closeOsmFile();
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As this is a test script the output is to the console rather than to a file. Needless to say the script is untested!