We were a bit perplexed a few weeks ago when Google announced its $79 wireless charger. After all, there are other 10W wireless chargers out there for much lower prices. Then, we found out only Google's official Pixel Stand can charge the Pixel 3 and 3 XL at full speed. Oddly, other wireless chargers still displayed as "Charging Rapidly" on the phones. Google appears to have fixed that in the November OTA.
Google's Pixel Stand uses a custom wireless charging system on top of the Qi standard. The phone connects to the stand with a custom "handshake" to identify that it is a Google-certified charger. At that point, it charges at 10W instead of 5W as on other wireless chargers. At launch, the Pixels just labeled all wireless charging as "Charging Rapidly" on the lock screen and ambient display. After the November update, we can confirm that non-Google wireless pads display as "Charging Slowly" on the screen.
It was, of course, incredibly misleading to have all wireless chargers display the fast charging message. This feels like a bug that Google wanted to quietly fix—the Pixel changelog didn't even mention it. We asked Google on numerous occasions if the "rapid" label was merely an oversight but never received a response. We've reached out again and will update if we have any additional information to share.