Mailchimp had sent us the following:
We do not have an API version 3.3. Our API is currently on API version 3.0. This sounds like this is the version of the integration build. You would want to reach out to the support team of the integration you are using to ensure that they are utilizing API 3.0 to prevent any issues in June.
Anyone know how to fix this? As per June we won’t be able to use the current integration anymore and we don’t know how to change it.