Your handwriting may be garbled and slanted if your tablet is set to mouse mode.
Symptom
Handwriting is garbled, and it slants downward and to the right.
Solution
This happens when the tablet is in mouse mode. Put the tablet in pen mode.
Your tablet setup software, such as the Wacom Tablet application, should have a setting for pen mode or mouse mode. There may be certain situations in which your tablet software automatically switches modes. See the documentation included with your tablet software.