Yes, pressing on the "go-slower" pedal increases Regen, by design.
The exact mix of percentage of Regen and percentage of Disk Braking has not been well described here, I believe.
Remember, at 100% SOC you get NO Regen (so energy is wasted in ANY braking), but at 80% you do get the "full/designed" Regen effects.
At 100% charged, in ECO mode, do you notice the lack of the "normal" ECO-mode foot-off Regen?
Presumably, you should just be "coasting", unless Nissan applies the mechanical brakes
to "simulate" the expected Regen.