I received an email stating there was an error with their flash sale. It did state I got the email due to being a member. I am sure the code will work for others too.
This is what the email stated:
Flash Swimwear Sale: Save 30% on full price Womens, Mens, Junior & Kids swimwear. Enter code FLASH30 at checkout to receive the discount. No further discounts apply. Offer ends Wednesday 2nd March 2022 @ 11:59pm EDST. Free Shipping when you spend $100 or more ( after discounts ). $10 Shipping will apply if value of order drops below $100. Free returns on all orders through ParcelPoint. Find at more at www.zoggs.com/en_AU/delivery-and-returns
The code is displayed in the banner up the top, looks like it's fine for anyone.