Questions about Antenna distributor coax coupling - 2 coax plugs

The signal quality itself does not suffer. The adapter simply has a certain attenuation that weakens the signal.
This does not matter if the TV socket is properly levelled. However, if the signal from the wall socket is only just sufficient, this can lead to reception problems. In that case, however, it is a case for your signal provider anyway. A technician can measure the signal with an appropriate