To Uniform Vector
StatValueAdapter_FloatToUniformVector3 converts a Float Stat into a vector with the same value in every component: v → (v, v, v).
Example
Movement Speed is one Float, but the movement modifier it feeds is a Vector3 Stat. LinkerDefinition_SpeedToModifierInjector_3D (General Expansions) links MoveSpeed into MoveSpeedModifier_Vector3 with a Combine Flat Linker that reads it through StatValueAdapter_FloatToUniformVector_3D:
MoveSpeed = 6 → (6, 6, 6) → added to MoveSpeedModifier_Vector3 on every axis.