Some 7.5W Wireless Fast Chargers Limited to 5W as of iOS 13.1
ChargerLAB has tested wireless charging speeds on iPhone 11 models running iOS 13.1 and found that multiple wireless charging pads that were able to charge the new iPhones at 7.5W on iOS 13 are now limited to 5W.
Unsurprisingly, the decreased power lengthens charging times, as visualized in ChargerLAB's graph below:
The report claims that exceptions include various wireless charging pads from Belkin, Mophie, Native Union, Anker, and Logitech sold by Apple Stores, leading ChargerLAB to speculate that Apple may be limiting 7.5W wireless charging to pads using fixed-frequency voltage regulation as of iOS 13.1.
Apple refers to fixed-frequency 7.5W charging as "Apple Fast Charging" in some product listings on its website, but the technology was incorporated into the Qi standard last year, so it is no longer proprietary and seemingly should not require certification under Apple's MFi Program to incorporate.
We've reached out to Apple for comment and will update this story if we receive any new information.