iPhone discharges while being on charger

[dotck]

I've seen this several times already, but it only happens once in a while. When I plug in my iPhone before I go to sleep, it confirms it is connected to the charger and the bolt symbol is being shown at the top right corner, so my expectation is that it is actually charging the phone. The next day I wake up and the battery is almost discharged. Not sure if it is a software bug or hardware issue. Has anyone else experienced these issues?

iPhone 7 (2016), battery replacement in 2018 at my local Apple Store, current capacity is 89%. iOS 13.3.1.

 

[Lekro]

It's this component that's bad: https://i.ebayimg.com/images/g/EQoAAOSwBwdaghiG/s-l300.jpg
It's called "Tristar" (U2) USB IC. It controls charging also. This defect can happen when you use a non certified lightning cable to charge your phone. The certified cables have a security chip in them that talks to Tristar that the voltage is safe and filtered.
If that chip in the cable is fake, and does no voltage regulation, Tristar (the next fail-safe for voltage irregularities) becomes a punching bag and will eventually fail due to voltage spikes.

A repair shop can help you. Apple offers a paid device replacement for this defect. Assuming it is out of warranty, of course.