Mouse is painting, stylus is erasing I am using Blender 2.91 and a Huion stylus. I set up a simple mesh, with a texture material, and switched to texture paint mode, using the default brush. Everything is working great when I use the mouse, but when I use the stylus it's behaving like an eraser and it's clearing whatever I touch to alpha 0. See video below.

Larger image. Left screenshot is what I get after left-clicking with the mouse and dragging; right screenshot is stylus-down and dragging.

What's going on?
Some ideas
Could it be a virtual/button/mapping issue of some sort? Under which condition the same thing would happen when using the mouse? Maybe if a modifier key is pressed?
Even though the poster was having a different problem, one of the answers to another question Painting problem when using pen in Blender seems to do the trick for me. If I change the Preferences &gt; Input &gt; Tablet &gt; Tablet API to Windows Ink then the stylus paints with the selected color.
I have no clue why this is happening though; I will accept any answer that sheds some more light on this issue.