The Australian quartet of Flynn Southam, Edward Sommerville, Olivia Wunsch and Milla Jansen obliterated the previous record by more than a second and a half.
2023 World Junior Championships: Day 2 Finals Live Recap swimswam.com - get the latest breaking news, showbiz & celebrity photos, sport news & rumours, viral videos and top stories from swimswam.com Daily Mail and Mail on Sunday newspapers.
The 2023 Worlds Juniors will be a showcase of the next generation, all of whom will look to make a name for themselves and factor into the 2024 conversation.
"I am hoping with more training and more time I can snag a spot on the (4x200 free) relay next year at Olympic Trials," Hayes said ahead of World Juniors.