In the rare case there is a prior referral, yes last click attribution comes into play. But that's the same for every shopping extension (Rakuten, Capital One, etc). The extensions have to comply with the affiliate network's "stand down" policies, which means they can't just automatically pop-up and actively try to poach the commission if it's within the same shopping session. And they all comply. MegaLag focuses on a very niche case of going back to the merchant in the same month.

Source: I worked in the affiliate industry for a few years