The theme of the Met Gala this year was "Costume Art", so the idea was to reference art. This is the whole Madonna look
It's actually a reference to a pretty cool and obscure 1940s surrealist work, The Temptation Of Saint Anthony by Leonora Carrington
Madonna is very good at surrounding herself with creative people, but what cheapens it a bit is who she is embodying.
The painting was largely inspired by a Victorian novel, La Tentation de Saint Antoine, which imagines that visions of the Queen of Sheba was one of the temptations. The figure with a boat hat and bugle is sometimes interpreted as the Queen of Sheba, although that's probably the figure in red.
The whole thing with the Queen of Sheba is she was super sexy, and in Kabbalah specifically she's linked with Lilith as a symbolic of the demonic unholy seductive aspect of the feminine. So this is probably Madge trying to communicate she's a succubus.
That's a chick that photographs weird.
Here's her from her Love At First Sight video:
Which I think looks like actual dogshit.
Then here she is from Get Outta My Way and Time bomb where she's a smoke show: