Yes, I'd consider the charging hub defective if it cannot charge above 50W with the battery's SoC below 50%. The battery does adjust the charge rate dynamically once nearly charged, but you could expect 60W rate most of the time.
Ok, so I just plugged in the charger to the drone directly, and I'm getting about 57-58W or so. So you think I may have an issue with the battery pack charger?
I have the exact same one (along with another wall plug Anker charger and a couple of their power banks) and always get ~65W out of it. Using it to charge the Avata 2 I'd get either ~30W or ~60W depending on the battery's SoC and whether the hub...