Using this post as an example:

https://lemm.ee/post/16379151

In the Web UI, it renders as a dropdown Element that needs to be clicked in order to show the images.

In Boost (and other apps I tried), it displays "spoiler spoiler" at the beginning of the post, but doesn't hide anything. Would be great to get properly rendered spoiler tags.

The images in this post I had to manually embed by using the code ![description](image link). It would be great if the formatting shortcuts in the editing window had a button for embedding a picture hosted externally that inserts this code.