Because the character is appearing?

The film is call Doctor Strange in the MULTIVERSE OF MADNESS…so the answer sort in the title.

We know she's going to appear. I think we even see her shield in the official poster.

Yeah it is

@Thegodlynoob543 Captain Carter's Shield is on the official movie poster.

Look at the cast list. You'll see Haley Atwell as Peggy Carte/Captain Carter

Because im in it

Look under Wanda’s eye on the right

At first we saw her shield in the poster and then Disney confirmed it

When did disney confirm it?