Google Discovery campaigns will be replaced by Demand Gen (basically Discovery Max, now with YouTube Shorts placements (and more)) campaigns this fall.
But if you don’t want to wait, you can sign up for the beta now.
More on Demand Gen from Google Ads Liaison Ginny Marvin:
Demand Gen campaigns combine image + video ads in one place and can be used to drive conversions, site visits and actions like sign-up and add-to-cart across YouTube, Discover and Gmail