Marina Shafir confirmed on her Instagram Story that she's at the arena along with Ronda Rousey, Jessamyn Duke and NXT Women's Champion Shayna Baszler.
There's now obvious speculation on the Horsewomen making an appearance on SmackDown, but it looks like they are filming for the WWE Network, likely an episode of WWE Ride Along. Rousey has been away from WWE since WrestleMania 35, but she lives on the West Coast and WWE production crews may be taking advantage of her being nearby to get some filming done. It's very unlikely that the Horsewomen would spoiler a potential main roster appearance on social media.
Fans on Twitter were also tweeting about seeing the Horsewomen in the parking lot of the arena.
You can see a video of Shafir's Instagram Story clips below: