So as of Nemesis, we know that Lila can shapeshift into anyone, including one of the heroes. Marinette even says “including us”. But they also say that Lila had shapeshifted into all three of those people who were taking the earrings and passing them on. Now, why would she do that if she were truly unaware of the Miraculers following her? We know there must be a mole. I don’t think it’s Aglae, since that’s too obvious and I’m sure that’s a red herring.

Since the beginning of Season 6, Rose has been visibly worse. She is paler, and has lost a lot of hair. This indicates that she is far sicker than we could have imagined. My theory is that either at the beginning of the season or some time near the beginning, the real Rose was switched out with Lila-Rose, and Lila-Rose took her miraculous. The real Rose is in a hospital somewhere away from Paris because of her sickness, and has somehow been cut off from contact with the gang. The real Rose is going to die in Season 7, the gang’s going to find out, and they’ll realize the Rose they have with them is not the real Rose.

They would find out right after fighting an akuma, while Lila-Rose is still Pigella or has just detransformed. The camera will do that thing where it pans over Marinette and her eyes go wild and bulgy like in a horror movie.

So yeah. Rose is fucking dead theory, everyone