Ctrl+f clipboard, no results. What does "Secure Clipboard" in the title refer to?

The release seems to be only the SMS/RCS app, rest is future:

> We're also going to be overhauling or fully replacing the rest of the AOSP apps in the near future. AOSP Gallery is incredibly outdated and is being entirely replaced. AOSP Keyboard may be similar. We recently hired a bunch of new people and will be hiring more so our progress will be accelerating.