The best it can do is have bold type for unread posts in the title. I usually click the first page if new topic or use the arrow to go to the last page which is an OK, not great, solution.

Or, you could view it in full site and when you find the post you want, scroll down and change it back to mobile.

I seem to remember that @EvilGreebo and @lexnaturalis remarked that the mobile site is version 4 compared to version 5 for the full site...