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.
If I type in the comment field above. Keep the text, and try to click a navigation: midwest.social Communities, Create Post, Create Community. They fail to go. Once I submit (or clear the contents), I can navigate on top again.
Dies was a really bad choice. They are disabled, non-active, when text exists in the comment box. Just verified it here at home on Chrome as well. Going to copy login to Firefox and see there.
And on Edge, same behavior. (All these are on desktop Win10 environment).
"Navigation Bar Disabled while text in comment field" would be a fitting description.