Hello!
I have moved into a townhouse built in 1951, two floors plus a basement. I have opened a sliding door between two rooms on the first floor (pink marking). I'm not sure it has always been a sliding door, but there has always been a door there. The entire opening is now about 160 cm wide, and then we opened 20 cm more above the door. The builder said it's not a load-bearing wall. I would like to double-check on this forum as well. See pictures.