Sam Raimi didn't wait until the post credit scene. I guess.

Raimi didnt even watch WandaVision

In universe explanation: she moved

Irl explanation: sloppiness

A sorcerer did It (?

She didn’t go after her kids because she thought they were in danger. She missed them so much she just wanted to be with them

Inconsistencies are bound to build up in massive story telling like the MCU. I came up with an in-universe explanation for why stories don't line up based on the theory that reality can shift and a universe viewed from outside wouldn't make perfect sense because the laws of quantum physics might allow for multiple versions of the same reality to exist, not as just completely separate realities in the multiverse, but realities that can merge together as well.

This idea has been suggested in real life. Two people in the same reality can experience slightly different timelines, and when they interact those timelines, merge causing inconsistencies in reality that are not perceived by those living in the reality....at least mostly. It's not uncommon to go back to a place that seems to have changed even though it hasn't for years, or to watch an old movie and see scenes that are inconsistent with very clear memories of the film.

It's just a theory.

Waldron Moment