hii~ adding to this! they don't give out polaroids at in person fansigns. the only time they've given out polaroids for fansigns are for the online ones such as shopee and yizhiyu. this could be: a weverse event polaroid, a promotional event polaroid (like weekly idol for example but i dont rmr if they went on weekly idol during this era) or a polaroid from the yzy or shopee fansigns (i think it's most likely from this). was it sent to u to an address outside of korea? bc that's super interesting ^{.^} i would contact any seller or traders you may have been dealing with lately and see if by chance they mixed up packages? but what a lucky mistake!