Just out of curiosity can someone point me to the basis for the claim that diagrams are uploaded to some cloud storage? I've used the tool and had the impressio

Just out of curiosity can someone point me to the basis for the claim that diagrams are uploaded to some cloud storage? I've used the tool and had the impression that it was all client side in memory DOM stuff until I downloaded my diagram. I never looked if some of the content gets pushed elsewhere, how would I substantiate these claims?