Obviously there are tons of theories as to what causes those issues, but in this case the lever difference in the MT420 seems to have cleared them up. I recently wrote about the Hayes Dominion T2 brakes, and they compare favorably to the MT420s.

Brand: Shimano
Compatible Brand: For Shimano
Position: Front & Rear
Brake Type: Disc Brake - Hydraulic
Manufacturer Warranty: 1 Year
Compatible Bike Type: Universal, City Bike, Electric Bike, Folding Bike, Gravel Bike, Mountain Bike, Touring Bike
Set Includes: Caliper
MPN: BR-MT420
Country/Region of Manufacture: Malaysia
Number of Items: 1
Part Type: Brakes
Colour: Black
EAN: 4550170875077