Plan loaded for 10 minutes, so I only saw the KG. OK, from the reinforcement plans we understand that it is a reinforced concrete slab with d=12 cm and the wall with the arch is load-bearing.
In my opinion, the arch can definitely no longer support itself. But it doesn't have to. There doesn't need to be a beam over it either, 4m is freely spanned by any reinforced concrete ceiling over any length. The wall on the upper floor, in my opinion, makes no difference.