You are serious. Authentic kung pao chicken still needs to be eaten in Sichuan. In order to meet the survival needs of the local market, it has to be slightly modified outside Sichuan to meet the taste needs of local people. For example, I'm from Guangdong, but I basically don't eat Cantonese food outside Guangdong because it's not authentic (which is often not because the chef is poor, but because local restaurants have to do it to survive). Therefore, putting vinegar in kung pao chicken is a variant of kung pao chicken's practice. In fact, in terms of kung pao chicken's popularity, it is not surprising to put anything. The historical estimate of vinegar is really impossible to verify.