Darcy detects unnaturally high levels of "Cosmic Microwave Background Radiation," which she defines as "
relic radiation dating back to the Big Bang." It's unclear how this cosmic radiation ties into the story of
WandaVision, but comic book readers will immediately recognize it as a reference to the raw energy of creation in Marvel Comics - and the source of the Fantastic Four's powers. Marvel has recently confirmed a
Fantastic Four film is in the works, so this can only be direct setup for Marvel's First Family. It's possible that,
in the MCU, the Fantastic Four are connected to SWORD; note that Director Hayward has a strong reaction to the mention of cosmic radiation, and claims to still have teams of astronauts missing.