During this 4h period the phone was mostly in idle. I might have checked my notification some times, but that's all. 10min screen on time at max.
I measured with a usb volt meter about 480ma power draw, so that should be fine. Also, my older phones (Xiaomi, Google and lg) still charge fine.
Btw, calling it Dock might be a bit overrated, it basically is just a usb cable in a stand 😉
I also tried different cables but with the same result.