dang I didn't realize the mastodon "max photos" limit of 4 also applies to federated posts from other software. For example, this post has six panels attached on the original Akkoma (Pleroma-fork) instance:

https://fops.cloud/notice/B6h4zZnZ6zfM8AcGcS

But looking at it both from the mastodon web interface or Phanpy I only see four, even in the paginated view :(