thanks to Edrard (Wot-news owner) for this information. SU-76I was indeed officially removed from the premium shop. This decision came from Minsk. Here’s what a Russian representative told Edrard about the matter (private conversation):
“In short, we introduced it into the shop, then we saw the statistics after first few days and came to the conclusion that the tank is not suitable for selling. We will remove it from the shop. Everyone, who bought it, can calm down, it will stay in their garage. We will think further what to do with it. There is no information on when it will return to the shop, we will think about what to do.”
As I told you, it was OP and therefore it was removed. Oh well.