I eat a lot of blueberries and purchase them year round and I definitely have experienced exactly what you are referring to with BBs from Peru. They tend to be larger and look good in the package but have almost zero taste and the texture tends to be soft. The ones from Chile aren’t much better so I suppose the logistics in getting them all the way to grocery stores in the US means they get picked early and have a fair bit of time in transit to dry out and soften up. I am always really happy to see containers that indicate the blueberries are picked in Canada or Michigan since those seem to have the best taste and texture. Unfortunately it will be a little while before that harvest is ready and if you ever have a chance, definitely try and locate an orchard in your area and pick them yourself; if you like blueberries even a little bit, that experience is worth the drive.
If you combine that rule with the ability to endlessly stack Draw 2 or Draw 4 cards, you have what I think may be the most evil version of Uno that can be played. We called it Thermo-Nuclear Uno (i.e. Mutually Assured Destruction) since you knew that dropping a Draw 4 would almost certainly lead to someone being buried in cards and it might even be you. Even if you manage to dodge the stack, payback is coming and you won’t get lucky every time. I can remember games that we would finally just quit after an hour since no one would ever be able lay down their last card. Merging two decks can make this even more brutal and cuts down on interplay shuffles too.