It's not a front end problem but network problem, so I can't provide details, but you can learn network proxy, like Nginx, 

I fixed this！you can use Nginx or Other proxy service

Not just these，I found that this website（https://nisplaysports.com/） uses vue/nuxt, so it is definitely not Hydrogen, but it can also use custom checkout, which is too strange. Can someone tell me how this is done