Calling the billing service in the application without installing the target package for the intent

Question

I just received an email from Google Play stating: “We found that your applications, indicated at the end of this letter, call the billing service in the application without setting the target package for the intent. This may allow the malicious package to bypass the Play billing system Store and access items that were not purchased. "

This game is developed using Unity3D. I do not have native knowledge about native Android. What to do in Unity3D so that this is fixed? Thanks you