Somehow, Kylo realized they were a Dyad offscreen at some point independent of Snoke, and Palpatine didn’t realize their connection was a “Dyad”-level connection until they were together.
It’s just dumb because the Dyad is never really explained outside of what Palpatine says at the very end of the film. We don’t even learn how Kylo knows they’re a dyad. I would almost suggest cutting the term to just not add to the confusion, but I feel like that specialness is necessary to explain how Palpatine can just drink Rey and Kylo’s Dyad Milkshake and get that Sith sugar rush.
I’m kind of leaning towards Hal and RogueLeader here. If we just ignore the specific term “Dyad,” the whole thing becomes a lot less confusing. We know that they have a bond, and that it’s super-powerful anyway, given how they can transfer objects between themselves; so it’s not wholly unbelievable that Palpy could harness that power for himself. How much does it add to the film to say, “This is because ‘Dyad.’ Buy the TROS Visual Dictionary to find out more about ‘Dyad’!”
That being said, here’s my stab at “becoming” a Dyad. I kinda don’t want to use it now lol; but in the interest of fair play, I’ll offer it as a suggestion: https://streamable.com/uorkfi
(Also, which line are we talking about by poppasketti?)
And Jar Jar - we already knew that their bond survived after Snoke’s death. At the end of TLJ, there’s that moment when Kylo looks up, and “sees” Rey entering the Falcon. And then she shuts the door in his face both figuratively and literally.
EDIT: We see in TLJ (before ‘Dyad’ was a thing) that their connection was ongoing, and that it could transfer matter between locations (the raindrops). Expanding on the Rey/Kylo connection was one of the few bits of connective tissue that J.J. tried to incorporate from TLJ, and it honestly works really well…until he felt the need to re-contextualize the whole concept under an arbitrary title.