This got me curious because I've never heard of this, atleast according to this study it does not cause liver issues if you use it properly, aka you exercise and don't just drink it casually.
"The results showed that when whey protein is used in an uninformed manner and without exercising, adverse effects on the liver may occur by increasing the apoptotic signal in the short term and increasing inflammatory markers and hepatotoxicity in the long term." - link
¯\_(ツ)_/¯ I have no clue how to paddleboard so I dunno haha, just took the pic