The EFF’s response is right on the money, as usual:

Communications platforms are not comparable to unsafe food, unsafe cars, or cigarettes, all of which are physical products—rather than communications platforms—that can cause physical injury. Government warnings on speech implicate our fundamental rights to speak, to receive information, and to think.

There is no scientific consensus that social media is harmful to children’s mental health. Social science shows that social media can help children overcome feelings of isolation and anxiety. This is particularly true for LBGTQ+ teens.

We agree that social media is not perfect, and can have negative impacts on some users, regardless of age. But if Congress is serious about protecting children online, it should enact policies that promote choice in the marketplace and digital literacy. Most importantly, we need comprehensive privacy laws that protect all internet users from predatory data gathering and sales that target us for advertising and abuse.

This warning label announcement just feeds into the right-wing “tech platforms bad, full of librul thought, must protect the kids by surveilling everyone and blocking the harmful (minority-focused) content” agenda.

Keep in mind that this is not happening in a vacuum; many states have already put in place age-verification for sites they deem ‘harmful’ (and California is considering one as well, so it’s not just braindead red states getting in on the surveillance action), and this directly makes the argument that social media spaces (and the speech on them) are harmful, and should be subject to government approval.