I had read many stories about Chinese sellers faking all sorts of devices, and now it seems I had to encounter it myself.

Pay attention to the number 30000 mAh.
The device was delivered, everything looked fine. It looks great and promises to be a good helper on trips.
I charge the little iPad (its battery capacity is almost 12000 mAh). But the iPad does not even charge halfway before the miracle device is already completely discharged. I charge the device, repeat - the same result.
I gave the seller negative feedback. After a while the seller writes that they will refund five dollars as compensation if I change the feedback.
I decided, just in case, to take the miracle apart and see what was inside. The worst fears were confirmed. Inside there was a lot of empty space and two 3000 mAh batteries. That is, instead of 30000, they sent me a 6000 mAh battery.
That is the story.