Yup. I don’t know whether this has been discussed already (I know the link between drugs and the glowing skull has already been found, but I’ve got no idea whether the following has been used as evidence for TD12), but just like the painting of the skull in Sherlock’s living room, TD12 is (unnecessarily!) lit by lamps and thus gives the impression that it’s glowing.
Why? To give us a clue that Sherlock’s been given TD12 as well? It would explain why we see Culverton Smith in Sherlock’s living room for a mere second in TLD:
Today I rewatched TST and TLD and I’ve found some other things that I really want to write down (even if it doesn’t make any sense. I just need to delete some information from my mind palace ;-)). But for now: goodnight, I really need to go to bed now ^^