User deletion

So I recently received the following in regards my Facebook login app

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Platform Terms 4.b: Your privacy policy must comply with applicable law and regulations and must accurately and clearly explain what data you are Processing, how you are Processing it, the purposes for which you are Processing it, and how Users may request deletion of that data.

During testing, we found that your privacy policy doesn’t explain how users can request data deletion. Update your privacy policy to include this information before you submit an appeal.

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So I understand I need to update my privacy policy, which should be easy enough.


My question is... is everything related to the user deleted or are there exceptions like invoices etc. or anything else like that