If you send Push notifications to your users, you may find that, over time, you are wasting resources by sending messages to inactive devices with stale registration tokens. This situation can affect the push delivery data reported, showing up as a dramatic (but not actually valid) drop in delivery rates.
To get the most accurate picture of message delivery, it is best to only send messages to actively used app instances. This is especially important if you regularly send messages to large numbers of users; if a portion of those users are actually inactive, the impact on your delivery statistics can be significant over time.
By enabling Push Token Cleanup, it automatically removes unregistered / uninstalled token from user profile based on distinct_id when a notification event is sent.
To activate Push Token Cleanup on your account, follow the below steps.