Just happened yet again, Cantarella ripped my Portal, essentially making my deck worth 12 less provisions, denying me a major thinning element, while transferring it to my opponent as they thin two worthless 4p cards in Round 1 and spam their thank you taunt. I functionally lost the game on the spot.
If Cantarella pulls a 4p card, that's on your opponent for 1) playing Cantarella in the first place taking that gamble; and 2) not combo'ing it with Location.
If Cantarella pulls a 12p or 13p card, there is no recourse to that other than accept the loss (or a heavily reduced chance of winning). In other words, the person playing NG has total agency in whether or not they want to take the gamble, or even just completely mitigate it by playing the Location. You, the opponent, have zero say in whether the gamble or risk is acceptable or not, you are just victim to whatever card they manage to rip from your deck, good or bad.
When it comes to deck interaction with your opponent, Gwent's design team has utterly failed. The game tries so hard to make it so RNG elements are limited, and then cards like Cantarella and Viper Witcher Alchemist exist (and clog, to some extent). If I wanted to play like that I'd just go play fucking Hearthstone.