The privacy policy of Privacy.com makes me question if they should be trusted with the detailed transaction information of their users. The policy does make it clear that they share personal data with third parties under, what they call, "controlled circumstances":

"With third parties, within the United States and in other countries, who may access data about you to perform functions on our behalf"

Here it would be nice to get a clear picture of what these functions are. If they are only for the processing of payments then this is fine (they actually mention this case in the second bullet point so my example does not hold). If these functions are to data mine my data for reselling to a third party advertisment network that would not be alright.