If you track your push campaigns with Google analytics, there might be a Delta between our statistics and the one provided by GA.
Accengage statistics : each unique click on the push notification will be included in the reactions volume in our dashboard. The Web push disappear from the user device once clicked, so there shouldn't be more than one click per user.
Google Analytics : Depending on the attribution model you choose, some of the Google Analytics visits recorded for a specific tracker are attributed to the same visitor.
By default, when the users are inactive for 30 minutes not leaving your Website, a new session will be added to the GA campaign for this user once the Website is displayed again. Also, all the direct sessions to your Website after a previous visit started with a click on the push will be attributed to Accengage. This means that some sessions in Google Analytics don’t follow a real click.
Here is a GA documentation explaining the session attribution process.