GDevelop flips the Y axis to be consistent with its 2D rendering. Because of this, the scale is negative on one axis and the sum is 1 instead of 3. It results in particles being 3 times smaller than expected.
I guess that using absolute scale values should fix the issue.
I'm maintaining an extension for GDevelop that uses three.quarks. https://wiki.gdevelop.io/gdevelop5/extensions/particle-emitter3d/
GDevelop flips the Y axis to be consistent with its 2D rendering. Because of this, the scale is negative on one axis and the sum is 1 instead of 3. It results in particles being 3 times smaller than expected.
I guess that using absolute scale values should fix the issue.