Meta Ads pixel in post-purchase Additional Scripts

// Post-purchase remarketing / custom-audience tagging that used to live in
// the "Additional Scripts" box on the Thank You / Order Status page.
analytics.subscribe('checkout_completed', (event) => {
  const { checkout } = event.data;
  if (!checkout) return;

  // Persist a first-party "purchased" flag so future sessions can be
  // excluded from prospecting audiences client-side, mirroring what the old
  // Additional Scripts snippet did with a cookie.
  browser.cookie.set('pp_purchased', '1');

  fetch(`https://graph.facebook.com/v20.0/PIXEL_ID/events?access_token=ACCESS_TOKEN`, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    keepalive: true,
    body: JSON.stringify({
      data: [{
        event_name: 'Purchase',
        event_time: Math.floor(Date.now() / 1000),
        event_id: checkout.token,
        action_source: 'website',
        custom_data: {
          value: checkout.totalPrice ? checkout.totalPrice.amount : undefined,
          currency: checkout.totalPrice ? checkout.totalPrice.currencyCode : undefined,
          content_ids: checkout.lineItems.map((i) => i.variant && i.variant.id).filter(Boolean),
        },
      }],
    }),
  });
});

Legacy pattern detected via: Additional[\s\S]{0,120}(fbq\(|connect\.facebook\.net)