poVoq While this is true that we can assume it, but it might not be obvious for "newbie" or "lazy" users.
matteocontrini That looks like a good proposal.
I feel on the mobile currently, at least it is a bit more obvious than on a desktop browser view. I tried this the old fashion way and found non-technical (impatient) people to use the Flarum forum (e.g. grandfather, grandmother, mother, father, wife, etc.) And that was one of the common confusing things for navigation.
Any home icon can help on either a desktop or mobile device browser. For desktop, it might help to also have some indication of going back home on the forum discussion title area. That area has plenty of real-estate, although it would be nice not to clutter it. Also, on the right hand reply/following/post navigation side bar can be considered in the desktop view as a place to put a return to home action.