When visiting "My Moodle" pages such as https://moodle.org/my/ there is no visual indication that the notifications (e.g. I currently see "There are new forum posts") are clickable to expand and see more info. There is a title popup that will appear on hover, but there's no reason to expect hover to do anything since it's not on a 'a' tag or anything else with a similar affordance. An expand-collapse icon (as used elsewhere in Moodle) would be helpful, as would changing the cursor on hover to show that the area is clickable.

It also seems that the no-js fallback is to make the icon (but only the icon) a hyperlink to the list of that resources in the course. It would be more accessible if the whole sentence was contained within the link, so there was relevant text associated with the link for accessibility reasons.

I've not had time to look further into it, but the hide/show appears to be setting the height via javascript, which seems an odd thing to be doing. You want the collapsed size changeable via CSS and you want the expanded size to be "auto". I don't see what's gained by setting this via javascript rather than just toggling a class name.

And while I'm here the message "You have upcoming chat" when you have multiple chats doesn't make much sense, and should probably be "You have upcoming Chats" (note the capital C as well as the plural).