Here’s what I did:
- Create a post using my own user.
- Unlist the post.
- Change the ownership of the post to be my sock puppet.
- Schedule the post to be published in a minute.
- Wait for the notification to my own user.
The sock puppet also got a notification that results in the spinner. It happened a minute or so before I got the notification. I assume related to changing the ownership, but it could be when I scheduled it to be published.
For what it’s worth, this is another Discourse instance than the one I first discovered the problem on.