Of course, we can't rule out the possibility that someone created their own chips, but my guess is the older keys weren't compromised.
When was the bc1 key transition announced?
To be clear, you suggest that the LE did not move funds on addresses starting with "1" but only in "bc1". What about addresses starting with "3", did chip mixer ever had these?
Yes, all were moved, including the ones starting with 1, 3, etc.... it's funny how someone will be such an idiot to keep private keys online! what if an hacker would had come and steal all the coins? 49 millions!
Most likely it was an LE honey trap. Now they will most likely go to coinbase and recover even more... steal all the coins even from honest people , mixing everyone together!
https://www.blockchain.com/explorer/addresses/btc/1BN93SAJmNtk67ev6kLPzek8FtBZDRfbdhhttps://www.blockchain.com/explorer/addresses/btc/1JFG1oj9HtgMJ2YEg3E3qn5wBvPaaWqpHo