i now have to dismiss this prompt after every comment?

Yay! It's no longer doing it now. Did you do something (presumably at the .app end) or was it a temporary blip?

Edit: spoke too soon - have managed to bring the bug back again now. It might be because I did actually cancel a comment, but now that prompt is coming up for everything I'm trying to post since.

For me, this happens only sometimes - and it seems linked to a delay in posting the comment.

If the comment gets posted immediately, then all is well. If there's a delay in posting, and it finally does get posted, then I see this screen.

You should only get that prompt after trying to discard a comment without posting