Thor: Love and Thunder is the collaboration of old-school and new-school Thor movies in the MCU. Taika Waititi returns behind the camera (and as the voice of Korg) to bring that Thor: Ragnarok vibe that completely rebranded the character. In addition, Jane Foster returns to the franchise after missing Ragnarok, and with her comes the attached supplementary players. Specifically, WandaVision star Kat Dennings as Dr. Darcy Lewis.
Darcy was first introduced as the comedic relief intern of Jane Foster in Thor (2011). Dennings reprised her in the same role in Thor: The Dark World. But in the first project of Phase 4, Darcy was thrust into the broader MCU in her first non-Thor franchise appearance. In WandaVision, Darcy was brought back with a doctorate in Astrophysics to help SWORD research the Westview Anamoly.
Darcy played a considerable role in WandaVision as an ally to Monica Rambeau and Jimmy Woo, as well as a liaison for Vision. Having experienced the events of the Disney+ series, Darcy has had a wild journey since fans last saw her in Thor: The Dark World. So when she arrives to support her friend Jane in Thor: Love and Thunder, one would think she wouldn't be able to shut up about "The Hex."
Thor: Love And Thunder Ignores WandaVision Events
When Darcy Lewis appears in Thor: Love and Thunder, she brings her patented levity to an otherwise emotional and somber scene. Jane Foster is receiving cancer treatment, revealing to the audience that The Mighty Thor storyline from the comics was being adapted. Darcy sits down and converses with Jane about her treatment, her approach to battling this thing, and of course, how attractive Chris Hemsworth's Thor is.
Notably absent from this conversation is any reference to Darcy's experience in Westview, as seen in WandaVision. This is very out of character for Darcy as she has traditionally been something of a blabber mouth. However, the Darcy of old would have found a way to mention her experiences with SWORD any chance she could.
But with this brief cameo in Thor: Love and Thunder, there is no mention other than a slight reference to her being "very busy" lately. So why would Taika Waititi and his team not allow fans to feel the connectivity with a subtle mention of Westview, or SWORD, or Wanda, or Jimmy Woo, or anything that happened to Dr. Darcy Lewis in WandaVision?
So Many Stories, Not Enough Time
The most straightforward explanation for this reference omission is simply time. Coming in just under two hours as one of the shortest MCU movies to date, Thor: Love and Thunder is very short. The runtime of this movie already hinders its ceiling by not allowing for specific plot points to be fleshed out to match their importance. Namely, the throughlines of Eternity's wishing well qualities and Gorr's daughter. So it makes sense that there was not enough time for Darcy to drop any WandaVision references.
There are also some questions about the tonal consistency of the movie, with a very melancholy cancer storyline weaved into such a hyper-comedic tone of the entire film. Taika Waititi is usually a master of this balance and attempts to do so again here. Perhaps Taika did not want to distract from the few serious beats in the first half of the movie.
Protecting Jane Foster
Another reason could be that Darcy knows that if Jane found out about the events of WandaVision, it would be another excuse for her to focus on work over her battle with cancer. Darcy spends this cameo trying to convince Jane that she should stop working, accept outside help, and either put her efforts into fighting this disease or enjoy what time she has left. Perhaps Foster's former intern wanted to keep her adventures to herself to prevent her friend from doing what she does best, overwork.
The holes become apparent when considering the circumstances. For example, when SWORD recruits Darcy Lewis as an Astrophysicist to help with the Westview Anamoly, it is presumed that they reached out to the leader in the field first. That, of course, was Dr. Jane Foster. So there is a good chance Jane is already aware of the WandaVision events, but that is not written in stone.
Protecting Wanda Maximoff
Darcy, along with Monica Rambeau and Jimmy Woo, forms a trio of rebels within the SWORD machine as the only ones willing to hear Wanda's side of the story in WandaVision. Being an Avenger and someone who has had a significant role in saving the world on multiple occasions, it is easy to understand why these three sympathize. In addition, Darcy, Monica, and Jimmy have had run-ins with various Avengers in the past in Thor, Carol Danvers, and Ant-Man, respectively.
However, this theory only assumes that Darcy is unaware of the events of Doctor Strange In The Multiverse Of Madness. Even if Darcy knew that Wanda assumably did not make it out of that movie alive, it is hard to believe she would still stand up for her knowing all of the horrific things she had done ON TOP of everything that happened in Westview, New Jersey.
Lastly, there is a good chance that Darcy cannot speak of those events because SWORD wants to keep everything hush-hush. Everything seemed very off the book in WandaVision as Tyler Hayward, and his team was aggressive with their approach to Wanda Maximoff. Therefore, it could be that Darcy is legally unable to discuss what happened under SWORD orders.
This doesn't hold much weight as Darcy was the one who stopped Hayward in his tracks and proclaimed he was going to jail. Darcy doesn't seem like the type to follow such rules anyway. She even has a scene in Thor: The Dark World where she is giving away classified information in front of Jane's date in London.
So there is no confirmed reason why the events of WandaVision were not referenced in Thor: Love and Thunder. The easy and boring answer is that there was not enough time, and it was not pertinent to the story being told. But the fun answer is that Darcy Lewis has a super exciting life of Astro-spy hijinks that she keeps from her close friend Jane Foster. Keep an eye out for the potential (yet unlikely) Disney+ spinoff Agents of SHIELD reboot starring Darcy Lewis and Jimmy Woo.