The risk of a stroke when in AF is about six (6) times what a 'normal' person will have at any age of comparison. However, the risk of a clot-induced stroke, that almost certainly being caused by a clot dislodged from the LAA, is still high for several months AFTER the fibrillation has been squelched via medications or by an ablation. This is why a competent cardiologist or EP will ask you to stay on a DOAC for at least six months, and why a great many ask their patients to consider having a Watchman implanted. If the six-month-post-implant TEE shows no leakage from a properly sealed LAA, then the patient may be advised to discontinue the DOAC if..............IF............there are no other comorbidities or known risks for stroke. Most elderly ablatees will be advised, strongly, to stay on a DOAC for the rest of their lives. It isn't cheap for many, I get that, but it's good insurance against deep vein thrombosis (it won't prevent all clotting, just retards it, and most people move around just enough when not on a bus, train, or airplane, or wheelchair, to prevent such events on their own).
So, yes, you are absolutely right....a subsequent clot and stroke may be due to something else than the AF and any clots lurking in the LAA. Those can't be helped when they happen, as in the instances in the previous paragraph. But the largest and greatest risk, of all risks associated with AF, is the one from stroke, and those are entirely due to that small grotto in the left atrial appendage.