https://en.wikipedia.org/wiki/Chinese_Internet_slang
https://radiichina.com/chinese-slang-666/
https://technode.com/2016/07/30/666-has-nothing-to-do-with-satan-lost-translation/
The Chinese language is rich in homophones, which makes it easy to turn numbers into proxies for words and phrases, like 88 (bābā) or ‘bye-bye.’ That explains why 666 (liùliùliù) refers to the Chinese word for smooth or skilled (溜, liù) instead of the devil.