strobing LED problem

strobe.ino

#include <FastLED.h>
#include <stdio.h>
#include <SPI.h>

#define LED_PIN_DATA 11
#define LED_PIN_CLOCK 13
#define NUM_LEDS 128
#define BRIGHTNESS 155
#define POT_PIN A0
#define POT_PIN_COLOR A3
#define LED_TYPE APA102
#define COLOR_ORDER BGR

CRGB leds[NUM_LEDS];

CRGB colorArray1[] = {CRGB::Red, CRGB::Blue, CRGB::Red, CRGB::Black}; // sanity
CRGB colorArray2[] = {CRGB::Green, CRGB::Blue, CRGB::Green, CRGB::Black};
CRGB colorArray3[] = {CRGB::Green, CRGB::Red, CRGB::Blue, CRGB::Black};
CRGB colorArray4[] = {
    CRGB(173, 216, 230),  // Light blue
    CRGB(255, 255, 0),    // Yellow
    CRGB(0, 255, 216),      
    CRGB::Black           // Off/black
};

CRGB* colorArrays[] = {colorArray1, colorArray2, colorArray3, colorArray4};

int prevColorIndex  = 0;
int prevBaseInterval = 0;

void setup() {
  delay(1000);
  FastLED.addLeds<LED_TYPE, LED_PIN_DATA, LED_PIN_CLOCK, COLOR_ORDER>(leds, NUM_LEDS).setCorrection(UncorrectedColor);
  FastLED.setBrightness(BRIGHTNESS);
  FastLED.setDither(false);
  Serial.begin(9600);  // Initialize serial communication for debugging
}

void loop() {
  pulseColors();
}

void pulseColors() {
  static unsigned long lastChange = 0;
  static int colorIndex = 0;
  unsigned long now = millis();
  // read the values
  int potRefreshSpeedValue = analogRead(POT_PIN);
  int potColorValue = analogRead(POT_PIN_COLOR);
  // map the values. Base interval should be between 1 and 6 milliseconds
  int baseInterval = map(potRefreshSpeedValue, 0, 1023, 1, 6);
  int colorArrayIndex = map(potColorValue, 0, 1023, 0, 4);

  int interval = baseInterval;
  CRGB* currentColors = colorArrays[colorArrayIndex];

  // if the color is "black" show it 3 times as long!
  if (currentColors[colorIndex] == CRGB::Black) {
    interval = baseInterval * 3; // Black color takes longer, e.g., 3 times the base interval
  }

  if (now - lastChange >= interval) {
    lastChange = now;
    colorIndex = (colorIndex + 1) % 4;  // Cycle through colors 

    for (int i = 0; i < NUM_LEDS; i++) {
      leds[i] = currentColors[colorIndex];
    }

    FastLED.show();
  }
}