I don't have it handy but there were posts on one of the tech Lemmy communities about it. IIRC, they claimed to have sourced their own 5nm but a teardown revealed Taiwanese chips.
I have never seen any source saying China claimed they have produced their own 5nm chip. They just release the laptop and international media claimed the chip was homemade until found otherwise.
Just like the current 7nm chip in some huawei phones and tablet. It was just launched quietly and international media went and advertised it for them.
If you read the current article carefully you will notice it's arstechnica and the parent article from the financial times making the claim of China having the 5nm chip not "China" itself.
It's actually two people that are "familiar with the move" and whose names aren't printed. I'm not super convinced by that tbh.
Secondly, if this company was actually close to this technology, why would they not be talking about it? This would be a huge boon for Chinese tech, and that's not the type of thing that normally comes from two randos to an international organization and is usually like a press release or something.