This article describes Anticipatory Auto Replenishments.
NOTE: This feature is automatically turned on with auto replenishment payments option enabled.
Anticipatory auto replenishments are automated deposits prior to upcoming renewals meant prevent service outages when monthly recurring charges such as DIDs, E911 and any associated USF are assessed.
This payment is executed 3-4 days prior to months-end and the amount differs from your auto replenishment option as It only calculating amount to cover the monthly recurring charges.
You can review this feature and check the amount under Preferences > Balance Management of your Manage portal.