The "southern treasure-free bodhisattva" you described is usually used to suppress evil spirits. Most people do this when they feel something unclean at home. Even Buddhists can't stick this stuff on the bed, because all Buddhists know that it is disrespectful to the Bodhisattva. I don't think it is possible for the host to be playful and stick it on, because it is impossible to stick it so tightly. So I think this is a special symbol. It should be able to suppress evil spirits.
Look at the whole house to see if it is gloomy, that is, a house with no sunshine or poor ventilation and high humidity. If so, it may be that the house is not clean and the landlord moved out because he didn't want to live there. When you entered the house, you also felt any strange feeling or discomfort. If so, it is recommended not to rent it.
I think this house may have a certain history. You can ask the surrounding residents to see if there is anything wrong with this house. Don't ask the landlord, because the landlord will not say anything.
"eh? Bamiyan "is a six-character mantra of Guanyin Bodhisattva, which is usually used to ward off evil spirits. Generally, it will be carved on some exorcism objects or large pillars of temples to suppress evil spirits. Usually, the six-character Daming mantra is also used to exorcise evil spirits or bless things.
I suggest that you should know the origin of this house. Because if it is really those dirty houses, it will not only affect people's health, but also affect people's luck.