This is just the front page of Google but you get an idea of what it says. The 'Warden's Heart' is just an idea, when in reality the devs are leaning more of towards it being sort of like the Ender Dragon without all of the xp and glory, just a one-time trophy.
Sry if it's a little blurry. I could quote what is being said if you would like. Also, watch some of Ibxtoycat's and Wattles 1.17 Snapshot videos, they go over what is being added and what the devs say about their ideas and future improvements to Minecraft or, of course, watch the devs themselves in their means of social medias.