> other 14 fake pubkeys won't do that hop obviously

Other *15* fake pubkeys -- the total ring size is 15 decoys + 1 true sender

> isn't your real pubkey...exposed...?

It depends. Some of the other 15 pubkeys might have, by chance, sent money around the same time you did; but even if they didn't, some other transaction within the same time frame might have selected them as a decoy too, so that it *looks like* that decoy might have sent money in the same time frame you did.

If neither of those happens, then your pubkey is the only one that shows up in a future ring signature, which might be logged as evidence that there's something special about it. Namely, the attacker knows two things: the "special pubkey" received money in one transaction, and then in a future transaction, it *might* have sent money.