I have found that the back button bar when accessing the forum via the mobile app has disappeared.
This is frustratimg when navigating to the previos page as I have to start from the top of the topic list.
Please add this back! 
Please guys! I need this back!
This is one of the times stuff with the forums go in Bug Reports 
You can use the discourse app (named Discourse Hub) and it will be there
Why was it removed from Ask?
I think it’s just a bug. I pinged someone to take a look
Any updates on this? Still quite inconvenient.