The origin of the abnormal Ether transactions that paid more than $5 million in gas fees seems to be Korean “exchange” GoodCycle.
Source: https://cointelegraph.com/news/alleged-ponzi-scheme-sent-the-5-million-in-ether-gas-fees
Alleged Ponzi Scheme Sent the $5 Million in Ether Gas Fees
June 17, 2020
CoinTelegraph