As set out in my answer to Parliamentary Question No. 925 of 26 July 2022, the automated US Electronic System for Travel Authorization (ESTA) system is controlled by the US Department of Homeland Security.
When an ESTA application is denied, I understand that the standard practice is that the reasons for a denial are not communicated to the applicant. You will appreciate that US immigration regulation and operations are a matter solely for the US authorities. Officials from my Department regularly engage with the US Embassy to discuss immigration and visa issues. The US Embassy, understandably, does not share details of individual applications.
I understand that prospective travellers to the US whose ESTA applications have been denied because they accidentally inputted incorrect information may seek redress via the Department of Homeland Security's Travel Redress Inquiry Program website. I am also informed that an ESTA denial does not prevent an individual from applying for a regular visa through the US Embassy. More information on this process can be found on the Embassy's website.