(CNN) — Kids love YouTube. The service is packed with ostensibly kid-friendly content.

But child, consumer, and privacy advocacy groups are claiming YouTube illegally collects data about under-age viewers. They want YouTube to change how it handles content for children and pay a fine up to “tens of billions” of dollars for allegedly profiting off young viewers.

In a complaint filed Monday, 20 advocacy groups asked the FTC to investigate the Google subsidiary for violating the Child Online Privacy Protection Act (COPPA), which limits how a company can collect data about kids under 13. Under the law, companies have to notify parents and get their consent before collecting data on children.

“Google has made substantial profits from the collection and use of personal data from children on YouTube. Its illegal collection has been going on for many years and involves tens of millions of US children,” reads the complaint, which