This just happened to me with a non-game, a magnetic usb charging cable and gives me the impression that that this is how counterfeiters operate. The original seller was the only source for the product for 3 months and stated that the US supply of it was at zero. Behold, around this time 2 "Just Launched" sellers appear that override whatever mechanism chooses the seller when you load an item page with multiple sellers. Now, in order to get the original seller you have to click the small link at the bottom of the item that says "X New from Price". Shady! Link to the item (original seller is Antau)

My issue is only when using the magnetic charging cable. The time it takes to charge with that cable decreases as long as I supply a higher 2.5A than when I charge it with the 1A on my external battery. But when charging using the USB 3.0 ports on a desktop from the front, it seems to take longer. I have never charged it with the oem charger. I also have a Antec charger, I could try that and see if it is faster.

Charging with the oem cable and adapter is fast. But I do have a magnetic adapter on the Go which makes that not possible since removing it means I have to remove it too.

I bought these

https://www.amazon.com/gp/product/B01MCZB2KR/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

I assume they can't charge as fast as GenX?