#!/usr/bin/perl
use strict;
use warnings;

my $decoded_json = {
    'version' => '1.0',
    'feed' => {
        'xmlns' => 'http://www.w3.org/2005/Atom',
        'updated' => {
            '$t' => '2020-10-16T19:55:33.294Z'
        },
        'gs$rowCount' => {
            '$t' => '1000'
        }}};

print $decoded_json->{feed}->{updated}->{'$t'};  # 2020-10-16T19:55:33.294Z