Across two decades, Nickelodeon hitmaker Dan Schneider has been at the center of hostile workplace allegations, #MeToo controversies, and now, the allegations that his tween-targeted shows overly sexualized its stars, among the likes of Amanda Bynes, Ariana Grande, and Jamie Lynn Spears.

“Sam and Cat” actress Jeannette McCurdy, who co-starred opposite Grande in the “iCarly” spinoff series, alleged in her memoir “I’m Glad My Mom Died” that a Nickelodeon “creator” (believed to be Schneider) frequently supplied children with alcohol and requested massages on set. McCurdy alleged she was offered 300,000 in “hush money” to not come forward about the abuse; she declined the payment. The claims mirror those that have followed Schneider for years, and the showrunner was fired by Nickelodeon in 2018 following an investigation that found he had verbally abused colleagues.

In a recent Insider report, dozens of former Nickelodeon employees ranging from female writers to child stars came...