Why I don't know but Sammy HDR+ photo look better. A friend tested on his v20 Samsung hdr+ Google hdr+ lgv20 hdr+ and light. ....something hdr+ and the best looking for what it's worth looked to be Samsung they were warm but crisp photos.
There's no window over LG [emoji4] there is a window for the camera and proximity sensor but nothing has built up there and you.can clean it out fairly easily I'm sure if anything did try to build up.