There's really none. The biggest evidence is the fact that an animal reservoir was never found and it was found relatively quickly during the first SARS and MER

There's really none. The biggest evidence is the fact that an animal reservoir was never found and it was found relatively quickly during the first SARS and MERS outbreaks. There's no evidence from the lab itself and no evidence the virus that reached the public was subject to GoF. And just general distrust of China.