Rebooting the device stops non-persistent exploitation and returns the device back to a Before First Unlock (BFU) state when you are not using it.

When a device is BFU, data is encrypted at rest and most OS components are not running which reduces attack surface and increases exploitation difficulty. BFU state is particularly troublesome for physical data extraction attacks that forensics companies like Cellebrite use, as they can't extract encrypted data. When a device is unlocked once after a boot cycle then there is greater attack surface, so we suggest automatic reboots to power the device back to this state when the device is idle or when you can't access your device so it is more secure.