IIRC the genesis of the dispute is that well before Qualcomm acquired Nuvia, Arm sold Nuvia an architectural license on the cheap, with the idea of renegotiating for higher prices if the startup became a successful company. Quacomm also owned an architectural license (they tried to do their own in-house core design before, with relatively poor results), and its price and royalty terms were commensurate with QC's status as an established company with deep pockets.
When QC bought Nuvia, QC tried to proceed with bringing Nuvia's designs to market based on the Nuvia license terms. Arm, on the other hand, insists that the license they sold to Nuvia doesn't automatically survive M&A transactions, meaning QC has to renegotiate terms for Nuvia-derived products.
There may be other stuff that one side or the other has thrown into the mix to increase odds of victory, but how much money is the real core issue. I have no idea who's in the right, or who's more likely to win.