This is just underneath the window trim, right next to the exit to the balcony. Bedroom
Located in Sofia, Bulgaria. 8/8 floor.
My girlfriend and I moved into this rental about a month and a half ago. At first we noticed we sweat a lot at night. We hung our laundry in the bedroom at first (one-two weeks give or take) and since it made sense this is what's creating so much humidity, we stopped. The night sweating improved a lot, but was still there. We open the window every other day for a few hours to air out the bedroom, but it still feels humid and wet, and I also noticed condensation on the window a few times. We noticed this buildup of mold today, just now. We asked our landlords (who used to live here) about it when we first noticed the humidity, and now today when we saw the mold. They said they haven't had any problems with humidity in the bedroom and have no idea what's causing it. They suggested we try out the drying function of the AC and we will, and in the meanwhile we'll sleep in the other room. Help us figure out this mystery?