Mastodon meta
My least favourite sharp edge of Mastodon is the fact that when you view someone else's post you only see replies to it that are known to your server - so there's actually a good chance there will be relies that are completely invivible to you, especially if you run your own instance
I'd love it if tapping a post kicked off a request back to the original server that fetched the current reply count, and provided a "view all replies" button if there were replies not yet visible to me
Mastodon meta
Note that replies are _usually_ sent to original post's followers, too.
(If you want to see how various Mastodon concepts (e.g. public vs unlisted) translate into ActivityPub concepts (e.g. `to` and `cc` lists), append `.json` to a post's URL and look at the ActivityPub object shown.)