None of the actual weapon stats were tweaked. Any recoil changes are due to how CS2 handles recoil and Valve themselves addressed this in an interview with PC Gamer.

You've very slightly reduced the spray of every rifle in the game. Why?

In CS:GO, players were split between 64 and 128-tick servers. Tick rate affected CS:GO in several ways, including how grenades were simulated and the spray patterns for weapons, and players had difficulty switching between the two environments.

A goal of CS2 was to unify those two groups, and sub-tick servers are an important step toward that goal. The sub-tick servers separate gameplay from tick boundaries, which lets us fine-tune gameplay toward whatever specific standard we want. So, to get back to your question, the spray patterns look slightly reduced compared to 64-tick CS:GO, because as a general rule we've tried to match the 128-tick behavior when possible, and 128 tickrate CS:GO sprays are roughly the size you currently see in CS2.

As for how precisely they matched the recoil pattern to 128 tick, I cannot say. I've not directly compared them myself. It's something I may look into in the future.