Look again at two features: the basket spokes and the bevel on the basket rim. No other driver looks like that.
Also, read SVS's propaganda, which is very similar to Tymphany's propaganda on the XXLS. Lastly, read between the lines of SVS's propaganda. When they use custom drivers, they like to trumpet that fact. Here, they trumpet having an "Exclusive SVS aluminum cone and composite dust cap***" What does that mean? The rest of it is an OEM platform.
Again, not that there's anything wrong with that. If anything, using the XXLS12 at that price point makes the sub a very good value. Well under the usual "5x parts cost" price tag one expects in speakers. Should they later on "update" the sub to use an in-house driver, the reason will probably be because the in-house driver will be cheaper, not better or even necessarily equal. The XLS/XXLS is a well-optimized, well-proven design.