Ask HN: On what grounds can I object to Meta using my info for AI training?

Meta have emailed saying they have a "legal basis called legitimate interests for using your information to develop and improve AI"

They provide a link to a form to object to this processing:

https://www.facebook.com/help/contact/6359191084165019

It asks the these two questions:

Please tell us how this processing impacts you. (Required)

Please provide any additional information that could help us review your objection. (Optional)

On what grounds can I object?