The team at Android always releases a devs-only preview for each new version of the operating system, but it's a tad early for Android 11's preview-which is why it was so surprising when the Android 11 Developer Preview page went live on Google (but less so when it vanished soon after). The public beta, meanwhile, will drop only in May, and it'll be more stable than the first developer release.
Whatever the explanation, it looks like Google is gearing up for some Android 11 changes. Another anticipated feature is "Share-to-Print" that will make it easier to print images and PDFs by adding universal "Print" option to the Android share sheet.
Android Police managed to grab a screenshot of the page before Google reverted the changes. If that changes, we'll certainly let you know.
Google is apparently going forward with plans to boost user privacy, which is excellent news for any Android user who will buy Android 11 hardware, or update their devices to Android 11.
Of course, since the company hasn't made any official announcements on this issue yet, the change was nearly certainly a mistake on someone's part, and Google has now taken down the Android Developer Preview page in its entirety. The list also confirms that native support for foldable devices is coming to Android 11, and seems to indicate that the new file sharing feature that leaked a few weeks ago is real.