Sorry to hear of your Power Controller issue with battery drainage, controller with black sticks.
I have the same Power Sky controller 2 with black sticks as you do, my experience is similar and have noticed quicker battery drainage but that was due to adding on amplifier boosters power source connected directly to USB port. Did a google search, others are experimenting the same as you with controller charging phone or iPad.
Plus, this particular controller uses a lower voltage Battery so any additional load will drain battery quicker. The original Sky controller 2 Battery voltage is higher, can handle larger loads.
Haven’t noticed my iPad or iPhone affecting voltage with this particular Sky controller 2 with black sticks, as mentioned above adding two amplifiers is draining voltage quicker. Can get about 1.5 to 2 hours use now, that’s with amplifier boosters on.
Also, Auctually disconnected amplifier boosters power source from controller USB and connneted directly to an outside battery source so Controller battery wouldn’t drain so quickly. Opposite happened, amplifiers continued to work but now the Controller Battery was being charged with the outside battery? Could have continued to operate but was worried Skycontroller would eventually have issues, so removed outside battery for amplifiers and resoldered power source from amplifiers directly back to Sky Controller USB port.
One fellow on a video with same battery drainage you’re experiencing, mentions to make sure iPhone or iPad are fully charged. Parrot will need to fix this hopefully on a future firmware update, hopefully your Sky controller eventually starts working on it’s own. Appears only certain phones and iPads are drawing voltage from this particular power Sky controller.