A Fraud Detection fraud rule can incorrectly make a false assessment due to NULL values.
The EXISTS and IS_MISSING operators assess a value as NULL if specified information is not provided.
For example, if you set the rule :billing_address_country: = :shipping_address_country:, but only provide the shipping address country in your payment request, the values that are compared are :billing_address_country: = NULL, which evaluates to false.
Empty values and white spaces are considered different. So when comparing two values that have different white spacing, they are assessed as different even if the text is intended to be the same.