One theory is that M&M and promptly released because China wants to send the message that they were taken in retaliate of the kidnapping of Meng:
"Many experts had expected China to wait a few months to maintain the claim that the two Canadians had been arrested for real crimes.
"The swiftness of the Chinese action signaled, instead, a more important message to the world from the governing Chinese Communist Party: Don’t mess with us."
https://asiatimes.com/2021/09/lessons-from-meng-for-the-michaels-prisoner-swap/
