Does their definition of CSAM exclude material that's not unlawful in the US? People can be (let's say) tactical about its inclusion from case to case. But I c

Does their definition of CSAM exclude material that's not unlawful in the US? People can be (let's say) tactical about its inclusion from case to case. But I can't say if it's the case here, nor how much it explains the 36 million not explained by other better replies.