If you type a comment, then change your mind and attempt to change pages. There's no prompt. So the UI just dies for no reason. Took me a minute to figure out what happened. Wound up refreshing the page.
Okay, it's disabled on Firefox as well. Though one caveat. When I click the heart next to Create Community, it does provide a popup:
This page is asking you to confirm that you want to leave — information you’ve entered may not be saved.
I'm expecting that popup for any of the navigation links with text entered (or really any reason as to why the link isn't working when it normally does). The lack of that message makes it work 'other than expected'.
As I write this reply, three buttons appear below the text dialog, "Reply," "Cancel" and "Preview." Not having deleted the text from dialog, nor committed to "Reply" or "Cancel," if I now decide to view your profile on this page by clicking your user name, it has no effect. This appears true of all links except !main and those to off-site URLs, for example, the donation heart you mentioned.
I also observe the "Cancel" button is not offered when typing a reply to your initial post.