Let me know your store URL and issue a screenshot or video for reference.
Well, which video link you have sent me is not working.
I have checked the store URL and I found there is no issue with add to the cart button. I can see add to cart button working correctly as per theme functionality.
I think you need to check your browser Or you can try live links into another browser or another PC to check it again. Then if you face the same issue then let me know.