Mine was the seal itself. noticed the wheel well filling up. Both the lights were fine, New boot rubber seal and dry as a bone since
Round rubber blanks next to the clusters?
Quite a common place for leaks iirc
the 2 black round spots either side of the boot ??
Yeah that's them. Probably be able to spin them. Means they aren't right against the body. Letting water in as it runs down the drain channel
I just went around the edges of them both with some clear sealant. Not had any issues since.