.39 fixed a bug where the congrats screen wasn’t showing when learning cards were due, which is why you may have only just noticed.
The good news is that the next beta will add the description to the congrats screen. The bad news is that a) images will be missing, and b) custom styling and JavaScript will be stripped. a) can potentially be fixed in the future, but I’m afraid for b) some sort of filtering is likely to stay, as we really shouldn’t be allowing arbitrary HTML and script tags in a description field.
Without CSS and JavaScript, you unfortunately won’t be able to achieve the look you have currently 
- though you could approximate gradual disclosure with HTML details tags. Remote links will still work, so one option would be to host more of the description online, and link people to it.
The overview screen remains unchanged for now - it will continue to show descriptions as before, and this will likely remain the case for at least the next few months. But the plan would be to eventually make it match the behaviour of the congratulations screen, so the text is shown consistently.