[ReignOfError]

As I understand the US Code, if a person is adopted, as a child, by a foreigner in a foreign country, that person can affirm their US citizenship upon reaching 18 years of age.

You misunderstand it. If you're born a US citizen, you remain one until and unless you voluntarily renounce citizenship as an adult. Adoption does not change that.

[Beckwith]

“You misunderstand it. If you’re born a US citizen, you remain one until and unless you voluntarily renounce citizenship as an adult. Adoption does not change that.”

Do you have a source/link, or just an opinion?