It's not good for the door to face someone else's back window. There will be light. Windows are also tuyeres, and tuyeres are turbid to tuyeres, which is not good for people's health. The door is mainly used to enter the wealth port, which is not good for wealth.
The solution is: invite more friends to your home, and you will naturally be carefree, and you don't have to hang any mirrors to ward off evil spirits. Do more good deeds and do more merits.