The design of Bluetooth buds is such that one of the buds is elected to be the receiver of data from the phone, it then propagates its signal to the second bud.
What you’re experiencing is a disconnection of one earbud to the other.
FWIW: apples AirPods Pro’s rehandshake (from the “slave” side towards the “master” side) every 10s- so you can have a lot of luck just waiting for it to reconnect; that is assuming that the slave device _wants_ to reconnect; it might believe it’s not in your ear.