Luffy, Black Beard and Shirahoshi are characters that may have been on Imu-sama's radar for some time now.
But why the focus on Vivi? It could be that Imu received recent information about her on Reverie.
But, what character could be related to Vivi that Imu-sama controlled to get important information? Well, Oda already hinted at who it could be. A character, who was not controlled by Imu-sama, but who works directly for Imu-sama and is a SPY.
And he is... PELL
Imu-sama is closely related to Imhotep, and even in the matter of possibly having a third eye, linked directly to the eye of Horus, the all-seeing eye.
Well, Pell is exactly the same. His conceptual design is exactly the same, and we can suspect he may have a third eye behind the bandana.
And you know what's most suspicious about this character? During Reverie, after the uproar involving Saint Charlos and Shirahoshi, Pell suddenly appears, giving a half-suspicious excuse that he was with Fujitora, and that's why he wasn't by her side to protect her.
The scene is so strange that even Vivi is in doubt and finds it strange. Why would Oda give relevance to this if it wasn't used later?
Well, we know where Pell was. He went to Imu-sama, his master, to pass on information about Vivi and even Pluton.
Pell is the traitor!

But why the focus on Vivi? It could be that Imu received recent information about her on Reverie.

But, what character could be related to Vivi that Imu-sama controlled to get important information? Well, Oda already hinted at who it could be. A character, who was not controlled by Imu-sama, but who works directly for Imu-sama and is a SPY.
And he is... PELL

Imu-sama is closely related to Imhotep, and even in the matter of possibly having a third eye, linked directly to the eye of Horus, the all-seeing eye.

Well, Pell is exactly the same. His conceptual design is exactly the same, and we can suspect he may have a third eye behind the bandana.
And you know what's most suspicious about this character? During Reverie, after the uproar involving Saint Charlos and Shirahoshi, Pell suddenly appears, giving a half-suspicious excuse that he was with Fujitora, and that's why he wasn't by her side to protect her.

The scene is so strange that even Vivi is in doubt and finds it strange. Why would Oda give relevance to this if it wasn't used later?
Well, we know where Pell was. He went to Imu-sama, his master, to pass on information about Vivi and even Pluton.
Pell is the traitor!