Anti-tracking blocked the signup form, so the form moved in-house
Brave and Firefox block MailChimp's embedded signup script under anti-tracking rules, so the Scyberia waiting list silently collected nothing. Replace the embed with a form we own.
The reason this is worth recording is that the failure is invisible from both ends. A blocked third-party script throws nothing the page can catch, so no client-side error handler fires and the page just looks like it has a broken button. And the analytics you would use to spot the drop is usually also third-party, blocked by the same rules on the same browsers, so signups appear to fall while pageviews appear steady, and the two numbers being compared come from different populations. The only reliable signal is server-side: your own request logs against your own form submissions.
Replacing the embed means reimplementing what it quietly did. Double opt-in, so a typo’d address does not sit on the list forever. Bot filtering, because an unprotected form on the open internet fills with junk within days. An export path, because a list nobody can extract is a hostage situation you built.
The shape that works is a first-party form posting to your own endpoint with a third-party service doing the sending. The collection has to be yours.