Either the puddle lamp lens under the mirror has cracked, or there is something blocking it.
It isn't too difficult to remove/replace the lens. All you need is a small screwdriver/pick. If you do need to replace it - you are half way there.
Hey OP, please post how to remove it. The video above didn't cover that. Hopefully there's a way to do that without breaking that clip. At least we know that the clips face rearward. You're going to replace the light anyway, but hopefully you can remove it without breaking it, to give us feedback . Good luck.