Doesn’t Arc use KLAC? Sounds like it did not accomplish its goal. And I’m not sure how you trace direct causation between cheating and decline in popularity. Plenty of games with rampant cheating (Tarkov) do just fine.
It's fair to argue I have no evidence of the cause of decline. I cite my frequent interactions with hundreds of players in the community, and streamers like Burnt Peanut. However this is qualitative, not quantitative. Me and my friends stopped playing because of the cheating, and so did every other one of my friends who picked it up. It wasn't that we wanted to stop playing the game. It was the cheating.
But I don't know since I don't play Arc. I'm just aware of a number of other games rife with cheating that remain wildly popular.