In his write-up of the final three Andor episodes, Alan Sepinwall notes:

In the film, Cassian seems to know nothing whatsoever about [the Death Star] when his contact tells him about Galen Urso’s planet killer. If you go back and watch that scene now, it either flies in the face of what he learns here on Yavin, or you have to read his reactions more as him realizing that Luthen’s information was correct.

This is a strange comment to make. Go back and watch the scene in Rogue One. Here is the dialogue:

Spy: I have to get back on board.
Cassian: Back to Jedha?
Spy: They’ll leave without me.
Cassian: Easy, you have news from Jedha? Come on.
Spy: An imperial pilot. One of the cargo drivers—he defected yesterday.
Cassian: [nods]
Spy: He’s telling people they’re making a weapon. The kyber crystals, that’s what they’re for.
Cassian: What kind of weapon?
Spy: Look, I have to go—
Cassian: What kind of weapon?
Spy: A planet killer! That’s what he called it.
Cassian: A planet killer…
Spy: Someone named Erso sent him, some old friend of Saw’s—
Cassian: Galen Erso? Was it?
Spy: I don’t know. They were looking for Saw when we left.
Cassian: Who else knows about this?
Spy: I have no idea. It’s all falling apart. Saw’s right. There’s spies everywhere.

I’ve put Cassian’s relevant replies in bold. He’s not surprised about a weapon; he wants to know what kind of weapon it is. In the Andor finale, standing before the Rebel Alliance council, he says he has no idea what kind of weapon Luthen and Kleya (via Lonni) could be referring to. All he knows is a jumbled list of names and places: Jedha, kyber, Scarif, Galen Erso.

I don’t see how this conversation in Rogue One undermines or contradicts anything in the way Andor leaves the story. Cassian heads to the Ring of Kafrene to meet with his imperial spy. He learns that (1) the Empire is mining kyber crystals (2) from Jedha for (3) the weapon that it’s building and, most important, that (4) the weapon is a planet killer and, finally, that (5) Erso—he supplies the first name—is bound up with it all. The information both confirms what he already knows and connects dots he hadn’t yet been able to connect. He isn’t surprised by mention of a weapon; he’s desperate to learn concrete details. His shock and surprise are at the scale of the answer. No discrepancy there.