Someone moved the bitcoin stored in the wallet of a challenge post days ago

I'm referring to this post:

Think somebody can guess or accidentally get your seed phrase? Nope, and I’ll prove it with free money.

Just checked the balance of the address and it shows that the 0.0001 BTC were moved on 19 October 2021.

My guess is that this was done by OP given that the account it was posted from is deleted now.