The tech news outlet Android Police has reported that the page developer.android.com/preview was found to point to a build for Android 11 - only to be snatched away again by Google soon after. This page purported to have brand new OS versions that could have been installed on Pixel devices. However, their external links failed to function while the blog tried to explore the new page.
Like all new Android DP landing pages, this one advertised changes compared to the current general-release version in terms of how apps behave within it, privacy controls, APIs and new features. Some of them also pertained to foldable support, Vulkan extensions and neural networks.
However, the blog subsequently reported that the page in question diverted back to its normal Android 10 status some hours thereafter. It contains very similar content in more or less the same design, just without advance insights into this OS' successor.
For example, the Vulkan version remains at 1.1, and the NNAPI version at 1.2. Therefore, it seems that someone at Google accidentally posted a work-in-progress to the live site, and the Android upgrade progress will continue at its usual pace throughout the year.