Update This bug was fixed in Patch 1.21.32 Problem My curtains are blue Cause This bug is cause by the curtains snapping to the windows. With the changes in Lighting in Patch 1.19, this leads to blue/purple curtains. Solution It helps to turn the windows but that’s not really a solution. BryonyRae found another workaround. Place the curtains on the wall Place the window. Since this bug is caused by the curtains snapping to the window, it can be prevented by placing the curtains first. This prevents the that curtains and windows become one.