The account was created ~11 days ago with the sole objective of receiving all the frozen funds.

Seems that somebody gained access to the keys and sent all the funds to bittrex 2 minutes after the fork with the following message:

''These are funds stolen by the Steem witnesses using HF23 May 20th 2020 - please return them to their original owners prior to the fork :)''

Now Bittrex owns the funds (they're not assigned to any client account).

Waiting the next chapter like...