I've seen the mirror lighting issue you're talking about in my own game. I've even contacted SimGuruArvin about it on twitter in July 2016! It has been happening a LOT longer than just the Cats and Dogs patches.
I also have my lighting settings on the highest but I've not tried on lower settings.
I would describe it as looking as though there is no ceiling to the room the mirror is in and the light is streaming straight in. But it depends entirely on what angle you are viewing the mirror from.
I've attached the two images I originally sent on twitter. The spa shot is on a custom built Lot and the smaller oval mirror shot is from the Goth household.
yeah...the light seems to have no clipping sometimes. I have a light in a stairwell up into the attic...when it is turned on, the light illumnates whatever is under or behind the staircase (even with settings turned down). It might be because I removed the back wall to the staircase to use under it for storage though. The mirror glitch is another story.
I was finally able to duplicate the mirror issue (cooler issue is reported here). I went to the Goth's lot, top floor, and put a mirror in that bedroom. I could then see the problem both in build and live mode. It depends upon where the camera is in relation to the mirror. From far away, there appeared to be no lighting issue, but as I approached the mirror with the camera, the area where the bed and chessboard are got brighter and brighter, then dimmer again as I backed away (see video below). This occurred with or without the roof (I tried deleting it). It occurred even drawing another room on top of that room. On the 2nd floor, I recreated it again, this time seeing it in relation to the angle of the camera rather than distance to/from the mirror. I tried removing all windows and then all lights; still see it. My conclusion is that it's definitely lighting from the exterior shining on objects reflected by the mirror; at certain angles/distances, the mirror must not be "seeing" the ceiling which prevents the objects from actually being lit (when you're looking at the room normally).
Video 1 shows the mirror placed in bedroom on Goth's top floor room. It first shows the actual lighting in the area of the bed/rug/chess and then shows how it changes when approaching/retreating from the mirror.
Video 2 shows the mirror placed in in the bathroom downstairs. It first shows the bathroom as-is, with lighting of the toilet changing as you swing the camera from left to right. Then the video shows the same thing after I removed all windows and light from the room.
Will add to our list.
