Block 9193687 (Link: https://etherscan.io/txs?block=9193687&p=1) contains 79 transactions, of which 75 have a gas price of 0. These transactions are also not all from the same address.
How does something like this happen? Is someone mining his own 0 gas cost transactions? But then why include other 0 cost transactions? Is it a badly configured mining client? Was the tx pool completely empty (is there a way to check that?)?
I realize most of the tx minted GST2 tokens, which is very advantageous to do for a low gas price, but still, a gas price of 0 seems very odd to me.