Fix vector normalization in JD (#17938)

Marlin/src/module/planner.cpp

@@ -2256,16 +2256,17 @@ bool Planner::_populate_block(block_t * const block, bool split_move,
         { steps_dist_mm.x, steps_dist_mm.y, steps_dist_mm.z, steps_dist_mm.e }
       #endif
     ;
-    unit_vec *= inverse_millimeters;
 
-    #if IS_CORE && HAS_JUNCTION_DEVIATION
-      /**
-       * On CoreXY the length of the vector [A,B] is SQRT(2) times the length of the head movement vector [X,Y].
-       * So taking Z and E into account, we cannot scale to a unit vector with "inverse_millimeters".
-       * => normalize the complete junction vector
-       */
-      normalize_junction_vector(unit_vec);
-    #endif
+    /**
+     * On CoreXY the length of the vector [A,B] is SQRT(2) times the length of the head movement vector [X,Y].
+     * So taking Z and E into account, we cannot scale to a unit vector with "inverse_millimeters".
+     * => normalize the complete junction vector.
+     * Elsewise, when needed JD factors in the E component
+     */
+    if (ENABLED(IS_CORE) || esteps > 0)
+      normalize_junction_vector(unit_vec);  // Normalize with XYZE components
+    else
+      unit_vec *= inverse_millimeters;      // Use pre-calculated (1 / SQRT(x^2 + y^2 + z^2))
 
     // Skip first block or when previous_nominal_speed is used as a flag for homing and offset cycles.
     if (moves_queued && !UNEAR_ZERO(previous_nominal_speed_sqr)) {