I want to throw another idea out there. I remember hearing comments, following Spider-Man: Far From Home’s post-credits scene, criticizing how Talos easily fell for a fake multiverse theory created by Mysterio.
If the Skrulls are involved in SWORD as Far From Home’s post-credits scene seems to imply, then they would presumably have knowledge of the WandaVision pocket-universe situation at that point as well, leading Talos to fully buy into the idea that he and his partner are actually chasing after rifts that were hypothetically allowing Mysterio’s fake dimensional creatures through.
If the Skrulls are involved in SWORD as Far From Home’s post-credits scene seems to imply, then they would presumably have knowledge of the WandaVision pocket-universe situation at that point as well, leading Talos to fully buy into the idea that he and his partner are actually chasing after rifts that were hypothetically allowing Mysterio’s fake dimensional creatures through.