I've created a custom environment texture (see below) and tried to apply it to the image. For some reason the texture comes out blue. The photo itself is not tinted (daylight-balanced floodlight and white walls), but when imported to blender it looks weird. I've tried a lot of things, including playing with color spaces (no difference) and adding RGBtoBW node (see below) and the environment texture still comes out blue.
What am I missing?