Adjusting Night Light scroll step size

When you hover the mouse over the Night Light / Night Color icon in the task bar, and scroll with the mouse, it adjusts 5 % each step. I want to lower it to 2 %. I have made that adjustment in a config file previously but I cannot remember how I did it. Can anyone point me in the right direction?

When holding shift while scrolling, step size is 1 % in Plasma 6