My guess is that the regenerative braking is set too strong on your scooter. The adjustments built into disc brakes are mainly intended to align the caliper with the disc.
The small adjuster at the lever (hydraulic brakes) only adjusts the position of the lever relative to the piston inside of the master cylinder. For reasons that my physics degree cannot explain, moving the lever further from the grip has the effect of making the lever feel stiffer even though it shouldn’t change the amount of slop in the lever or change the leverage the lever has vs the master cylinder.
Here’s a video we made about some of the basics of adjusting mechanical disc brakes on electric scooters.
-Paul from ESG