A goodwill repair is a repair done not because the issue is covered under warranty, but because the manufacturer wants to make the client happy. This could be because the item being repaired isn’t under warranty anymore, or because the repair is for something other than a manufacturing defect. The article is saying that Tesla is doing a lot of “goodwill repairs” that are likely actually for defects that would otherwise be classified as warranty repairs. It seems to be arguing that Tesla is doing this to avoid having the cars be classified as lemons, though it admits that another motivation for doing so is to adjust their financial reports as it changes how the cost spent for the repair is classified.