How do you make a copy of $headers?

Simply by assigning it to a new variable and using that...

my $headers = {
    'headers'       => {
        'Authorization' => 'Bearer ' . $Site::Variables::stripe_secret
+,
    },
    'agent'         => 'Wayfinder/v3.0',
};
my $head = $headers;
[download]

UPDATE:

Thinking about it, this only creates a copy of the reference and not a copy of the underlying hash...
Looks like I need to utilise something like Clone instead.

just save+restore 'headers' and its value as a ref, this is the only key being deleted, no need to clone. To deal in the longterm perhaps create your own post_form() which will restore the 'headers' key. That HTTP::Tiny behaviour is quite weird. I avoid to mess with user parameters unless i document it.