Stroke outlines are used by modifiers, fill tool, exporters, etc. When
the input strokes are not co-planar (different depths from camera view)
the end caps have smaller radii than they should have.
When generating the outline caps the normal vector is created from
the point tangents in 2D (after projection). When points have different
depths (Z positions) the tangents have a non-zero Z component as well
and discarding it leaves them unnormalized, thereby scaling the radius
by an unwanted factor.
Normalizing the vector fixes the issue. Object scale is now also taken
into account.
Pull Request: https://projects.blender.org/blender/blender/pulls/126687
e42b9a73be