M566 X900.00 Y900.00 Z12.00 E120.00 ; set maximum instantaneous speed changes (mm/min)
M203 X6000.00 Y6000.00 Z1000.00 E1200.00 ; set maximum speeds (mm/min)
M201 X500.00 Y500.00 Z20.00 E250.00 ; set accelerations (mm/s^2)
In your config.g file change the Z acceleration and jerk values to be a bit higher. As they are now they would cause some problems with mesh compensation.
Try
M566 Z60
M201 Z200
Can you share a photo of what you mean about the quality issues?