The commercials in each episode of WandaVision definitely have some sort of deeper meaning. While they initially seemed to be little more than Easter Eggs hinting at Wanda Maximoff's past, the past couple have really grabbed our attention, and today's included a major reveal you may have missed.
Promoting an antidepressant called "Nexus" that can "anchor you back to your reality," or even take you to a "reality of your choice," it initially seems to be a statement on Wanda's mental state. However, if the word "Nexus" rings a bell, it's because the Nexus of All Realities is a key part of the Marvel Multiverse in the comic books.
A cross-dimensional gateway, this Nexus provides a pathway to any and all possible realities, and is the point in the Multiverse where all realities naturally intersect.
The Scarlet Witch (and Agatha Harkness) tapping into this makes perfect sense, and would explain both the sitcom settings and how Pietro Maximoff appears to have been resurrected...in the body of a Quicksilver from another Earth (if that theory proves to be correct).
This Nexus would certainly explain what we (think) we know about Spider-Man 3, and why the Sorcerer Supreme's sequel is titled Doctor Strange in the Multiverse of Madness! There are only two episodes of WandaVision left, so we'll get some answers soon. Between this and last week's "Yo-Magic" commercial, these ads are becoming increasingly sinister.
Here's what the Nexus of All Realities looks like in the comic books: