Can someone help me orient myself?

I used to play cookie run Kingdom back in 2022 and was obsessed with it. I haven't played it since but I'm very confused. Im more interested in the characters/lore than the gameplay. Im always seeing cool fanart online. My main question is what's going on in the lore rn? I keep seeing shadow milk cookie and idk who that is or what his relation to pure vanilla cookie (my fav character) is. If someone can help me out, I'd be so happy! I tried using the crk Wikipedia but I ended up more confused.