Soooooo based on a similar experience, I don’t think it’s personal. Either the background check people get your information based on job history, or the applicant is asked for as much as they can provide. I get how uncouth it is, but in this case I think it’s an outlying circumstance.

I would reply and say, “I’m not answering all of that but I did work with (Jane Doe) back in 2017 and she was (type of employee) and performed her job (description you can give honestly).”