Shielding like you show above (with foil) doesn't decrease self interference, it only increases it, because it makes reflections, and signal bounces around inside the shield. Without the shield, this will not happen. This is why professional shielding will absorb the signal, not reflect it.
I agree but RF signal propagation it very complex and depending where this shielding is placed in relation to radiating element(s) it could result in signal cancelation from antenna.
RF Absorbers that attenuate signals is one solution.
I don’t understand why a RF reflector is not used to increase forward gain and then the use of RF Absorber material to provide shielding,
And which Made for Mikrotik companies use professional shielding in their products?