In the seventh episode of WandaVision, Breaking the Fourth Wall, the advertisement states:
Feeling depressed? Like the world goes on without you? Do you just want to be left alone? Ask your doctor about Nexus. A unique anti-depressant that works to anchor you back to your reality. Or the reality of your choice. Side effects include feeling your feelings, confronting your truth, seizing your destiny, and possibly, more depression. You should not take Nexus unless your doctor has cleared you to move on with your life. Nexus, because the world doesn't revolve around you. Or does it?
The advertisements are
controlled by Wanda, as is the rest of the hex.
This is obviously a reference to nexus events, which are explained in Loki. However, to create this, Wanda would have had to know about nexus events. There hadn't been anything to suggest this, nor are they common knowledge (in fact, it is impossible to know about them if only one timeline exists).
How did she know about nexus events?