Please use <code> tags to format your code and sample data! And you can omit the giant long ebay URL and replace it with some testing URL like http://www.perlmonks.com.
$response = HTTP::Tiny->new->get('...')
$response = get('...');
For the first request, you're creating a new HTTP::Tiny object and calling the ->get method on it. For the second request, you're using the get function from LWP::Simple, which is quite different. What you want is:
my $http = HTTP::Tiny->new;
my $response = $http->get('...');
$response = $http->get('...');
(Tested on URLs different from the OP.)