This feature has been removed or disabled as of Android 11 DP4 and Beta 1, and ongoing and persistent notifications can no longer be dismissed/minimized by swiping them away. Our original coverage of the change is below.
If you plan on just dipping into the latest developer preview for Android 11 with your Pixel 4 or 4 XL before proceeding back to normal life, be warned: a number of users are reporting that they cannot enroll in Face Unlock after reverting to a stable Android 10 build.
Today Google is releasing its third Developer Preview for Android 11. Unfortunately for the Android enthusiast crowd, all of the headlining tweaks in Google's announcement are developer-targeted, though we're guaranteed to find more changes hidden inside DP3.