Yes it’s account specific for Halifax too. You get offers depending on your use of debit and credit cards. I’ve got this 10% cashback offer.
I think the Halifax rewards works in s similar way, so probably account specific. Amex offers are the same
Santander have this as well but their policy is to offer a supposedly customised range of offers to each customer so it could be not all Santander customers will have the Butlins offer.