There is a lot of speculation right now that there is a traitor among the Vegapunks, including the Stella, or even a “betrayal” by Caribou (although the Straw Hats never trusted Caribou to begin with so it wouldn’t really be considered a betrayal.) This doesn’t sit right because all of the Vegapunks have a linked memory and linked perception, so they should be aware of one of them deviating from their plans.
We, the readers, are left in quite a stump after 1075. Someone on the island is overriding control of the Seraphim, the Stella Vegapunk is missing, and someone is shutting off all of the Den Den Mushi around the Labophase.
As we know, the only ones who can override the control of the Seraphim over the Vegapunks are the Five Elders. A panel from 1075 shows several Den Den Mushi being shut off almost simultaneously. If this is the work of only one person, they must be moving extremely fast.
As fast as the speed of light, which leads me to believe that Kizaru is already on the island, as well as Saturn, who has already overridden the Seraphim outside of where everyone is.
The reason they’re targeting the Den Den Mushi is that they know how powerful the Vegapunks, the Straw Hats, and CP0 are, so deactivating security measures can help prepare for a surprise offense. Some of the strongest, most important people in the world as they know it are currently in this lab.
In their sweep through the lab, Kizaru and Saturn also found the Stella Vegapunk in Kuma’s memory bank room. He may already be captured, or maybe he managed to hide/escape because he realized what was happening. He is the smartest man after all.
Bonney was able to avoid being taken or killed as well because she was inadvertently hidden inside Kuma’s memories at the time. The Vegapunks are not a part of some conspiracy among each other. Their enemies have already infiltrated the island, choosing not to make a grand entrance.
Theory by dynastistic (https://www.reddit.com/user/acosta9211)