Today, in a statement to The Verge, Google confirmed that its Pixel Stand was made specifically for the Pixel 3 and Pixel 3 XL in that these are the only two devices that can pull the fast 10W wireless charging current. Conversely, the Pixel 3 and 3 XL can only reach 10W wireless charging on either the Pixel Stand or any other Google-approved third-party Qi charger. Belkin has a 10W Google-approved Qi charger on the way that will wirelessly charge the Pixel 3 at full speed. We don't limit third-party devices, in fact, were working with our partners in the Made for Google program to get...
Source: https://www.gsmarena.com/pixel_3_capped_at_5w_wireless_charging_on_nongoogleapproved_chargers-news-33877.php