We are aware of the pressure issues with Apple Pencil, and will be releasing an update in 2-3 weeks that helps with this issue.
In the meantime,
if you are using customized brushes (like Kyle's), the ones with lower flow, I would keep the flow percentage at minimum 70% - 100%.
Also, with each brush, or at least the ones you apply more pressure, enable "Use Pressure for size" icon
We apologize for the inconvenience, and appreciate all your patience.
Let me know if you have more questions.