Sometime push messages are shown in the reports out side the schedule of Push Messages. For example, push was scheduled for 09/25/2020, however, reports push messages instances on 10/20/2020.
The “Users that Opened Push” report shows hits for when the user opened the push notification on their phone based on their device settings. Most users will open the notification immediately (assuming they open it at all) but some users will delay opening the notification. This could be days later and then the hit would be sent. The data on this report is inline with the assumption that the majority of users open the message on the day its sent with a small percentage opening it at a later date.