The changes between decades are explained in the series by changes within the fictional WandaVision program, which Maximoff is initially doing subconsciously when something goes wrong in that reality.
Her real identity is Isabel Matsueida.
Meanwhile it's those outside of Westview who are desperately trying to figure out what is happening.
At least it's not in the case of the Darkhold.
And in one single camera shot too, delivering one quick line.
She sought to help Wanda learn to control her reality-warping magic.