Apple has launched the iPhone 6s and 6s Plus repair program, which may have a power problem. The culprit is a component that Apple does not mention by name.
The problem applies to devices manufactured between October 2018 and August 2019. Everyone who bought a new iPhone 6s and 6s Plus should check its serial number through Apple support or an authorized service center. This will identify whether the device has the problem and is subject to free repair.
If someone has previously made the repair at their own expense, they can apply for a refund. To do this, also contact Apple or an authorized service center.