Bait and switch. The clause that says "The 3 months free Apple TV+ offer is not available if you or your Family have previously accepted the Apple TV+ one year free offer." is buried three levels deep, literally.
If you go to https://www.apple.com/apple-tv-plus you see a big banner advertising 3 months free, and a "check eligibility" button that goes straight to the buy for $4.99 app without saying anything about eligibility. You have to ignore "check eligibility" and scroll down to the bottom instead, find the hidden grey "terms" link, which brings you to another page of offers that doesn't spell out the terms, then click on the word "herein" to actually read the conditions of the offer.