Several complaints about the issue were expressed on the Reddit platform. Apparently, the reverse wired charging feature introduced in the iPhone 15 series may sometimes not work as desired. As a result, not all existing power banks with USB-C connectivity may be used with iPhone 15 models.
Response came from Anker
The problem affects many powerbank models on the market. It has been reported that the iPhone 15 specifically does not work properly with the Anker PowerCore Slim 10K PD. The manufacturer responded to the complaints and said that the only way to ensure that the external battery charges the iPhone is to use the USB-A port.
Offering a temporary solution for now, Anker will test all its devices to detect and fix this problem. It is stated that since there are many different power bank models on the market, it is impossible to make a definitive list of accessories that the iPhone 15 is not compatible with.