This is highly annoying, I sometimes accidentally hit the Posts button at the bottom and it'll take you to the communities page, but there's no way to return to your feed, you have to choose one of the feed options at the top which returns you to the 1st page at the top of your feed. And when on the communities page, the back button exits the app. Either make the Posts button return back to your feed, or the back button or just have a back button please.

This is on Android.