ETOPS is a safety regulation that prohibits airliners from flying too far from the nearest diversion airport. A higher ETOPS rating allows the flight to fly farther from the closest airport but has more stringent requirements, demanding higher operational costs.
As of 2021, there is no flight route over Antarctica, and flat-Earthers use it to “prove” a flat Earth. In reality, a reason for that is the lack of diversion airports in Antarctica, requiring aircraft with a higher ETOPS rating. Due to costs & the lack of market, no airliner considers it commercially viable yet.