Pictures of these models came out literally the same time pictures of that mock-up at Zhuhai showed up for the first time. So did the producers of these models have some insider knowledge and was okayed by SAC? I mentioned before I saw some CGI images of this version months earlier that I thought were from some fan boy. There were some fan boy art where someone put F-22 tailfins on the J-20 and I thought that was ugly. I thought the F-35 tailfins were ugly on it but the model looks better. Now I think those earlier CGI pics were from SAC and they've been leaking this out for a while.
These models are made by the company that made the model of the improved FC31 at the Zhuhai airshow. So they're not someone with some "insider knowledge", they can be considered "official partners".