Otherwise, the keyword use seems too generic to be used for this

I also feel that way, and I don't even understand how the word "use" is related to the underlying semantics at all.

My only guess is that use is already a keyword, and anything that's not a keyword currently would require a new language edition. I would also prefer something like autoclone async {}, or maybe even with_cloned <explicit list of objects to clone, or _ for automatic detection> async {} . Not sure if it 100% makes sense but would be more readable IMO.

P.S. it seems they will explore an alternative solution that doesn't involve a new keyword at all, and just automagically clones when it's "cheap" to do. Sounds more user-friendly to me TBH.