YouTube executives have warned creators over the last few months that changes are coming to the platform to comply with a federal children’s privacy law. Today, those changes enter full effect: targeted ads will now be restricted from running on kids’ videos, and kids’ videos will lose access to comments and some other community features. YouTube has said kid-focused channels will see “a significant business impact” due to reduced ad revenue.

YouTube will also begin running promotions for YouTube Kids, a separate app that filters the type of content users can see, on all kids’ videos. The app was launched by YouTube in 2015, and removes many of the features that are available on the main site.

YouTube told creators back in September that they’ll soon be required to “designate their content as made for kids or not made for kids.” The changes come as part of a $170 million settlement with the Federal Trade Commission over alleged violations of the Children’s Online Privacy Protection Act (COPPA). Anyone watching a video that’s been designated as made for children will now be seen as a viewer under the age of 13 years old, regardless of how old the user actually is. Targeted advertising won’t be run on videos designated as children’s content, and certain features including being able to send push notifications will be disabled.

“Many creators around the world have created quality kids content for their audiences, and these changes will have significant impact,” a new blog post from YouTube reads. “We’re committed to helping creators navigate this new landscape and to supporting our ecosystem of family content.”

“Many creators around the world have created quality kids content for their audiences, and these changes will have significant impact”

YouTube still can’t describe what content is “made for kids” and what isn’t, because ultimately it’s up to the FTC to enforce the rules. The FTC defines the category as being intended for kids, taking into factor what the subject matter of a video is, including if it emphasizes kids’ characters, themes, toys, games, and more. Whether that includes Minecraft videos or other games content remains a major open question. YouTube has recommended creators team up with their own legal counsel outside of YouTube if they’re concerned.

“We also use machine learning to help us identify this content, and creators can update a designation made by our systems if they believe it is incorrect,” the blog post reads, noting that YouTube may label a video as made for kids if a creator doesn’t. “We will only override a creator designation if abuse or error is detected.”

YouTube’s lack of guidance over the changes has creators concerned. Toy channels, for example, have a large adult audience and are ostensibly targeted at collectors, not just kids who want to play with them. These creators have already discussed changing their channels, and preparing for major monetization problems, in the coming weeks and months.

“Creators are being held directly responsible by the FTC,“ Dan Eardley, who reviews collectible toys on his channel Pixel Dan, previously told The Verge. “So if the FTC decides that [we] are indeed targeting children, we’ll be fined. That is frightening. It’s especially scary because the verbiage of ‘kid directed’ vs ‘kid attractive’ isn’t very clear.”

“It’s hard to know if we’re in violation or not.”

YouTube’s blog post notes that more updates — including more specifics on what type of content will be expected and what won’t — will roll out in the coming months. For now, creators are encouraged to voice their concerns to the FTC.