As you seem to have such a strong handle on the law around this area. I have a question, what makes false advertising not protected speech? And what do you see

As you seem to have such a strong handle on the law around this area. I have a question, what makes false advertising not protected speech? And what do you see as the difference between false advertising and fake news (where at the time of the writing is known to be false)? And no, I'm not referring to things that are clearly written for comedy or satire like the Onion, which is clearly protected speech and should be.