https://www.cnet.com/news/pixel-3-xl-rumors-google-launch-specs-release-date-price-leaks/

But with the Pixel 3 series, Google will want to avoid the mistakes associated with the Pixel 2 XL, which caught flack for burn-in issues and other defects related to the phone's OLED display. 

Those missteps resulted in quite a bit of media attention, marring some initial positive reviews with caveats. It also added a spotlight on Google's warranty policies, which were eventually broadened. (Note that the iPhone X's OLED display is not immune from burn-in either.)