I haven't gone back through this thread, or seen mention of this online, but...
I watched Wandavision. Then I started on Agents of Shield for the first time in months. I hated Season 3 and couldn't finish it, so jumped to Season 4. Binged episodes 1-4, and is my wont, let episode 5 run for a few minutes before shutting the tv off.
This is the episode wherein, in flashback in the first two minutes, the "ghost" people are shown finding the Darkhold.
They go into a basement, and pass a birdcage. There's a poster of a carnival advertising Quentin's Carnival on the wall. Another poster, this one of Voltarra, Mistress of Light. She's a blonde, but with a big "electric" afro. And then the Darkhold, hidden in the floor.
It's not an exact match up, obviously, but...holy smokes. That's a LOT of coincidence for one scene. Agatha's basement features a similar birdcage; Wanda creates a carnival (intentionally?); Monica's superhero identity (one of them) is Photon. Her powers are electro-magnetic based, most notably light. And then, big bad evil book.
I don't know what it means. Very likely it's just a fun throwback. But still...just how long have the threads of this show been around??