The advertised default fare is labelled as “zones 1-2” in the fare finder, which is clearly wrong.
If you use a zones 2-3 Travelcard on Oyster without any PAYG balance on this route, your Oyster card will be blocked after the first use because your PAYG balance will end up negative, similar to the widely-reported problem when Oyster PAYG first went live about two decades ago that many Oyster Travelcards stopped working and negative PAYG balance was found out after investigation.