Seeeduino XIAO SAMD21 Breaks When Powered by 220v Source

Have you tried reducing the number of LEDs?
For example, 4 LEDs?
Is your strip supported by “Adafruit_NeoPixel”?
Can you now reproduce the condition that worked as expected before?

The code below will only light one LED at a time, even though there are 192 LEDs, so there is no need to worry about current consumption.
Try it out by attaching it directly to your sketch.

#include <Adafruit_NeoPixel.h>

#define PIN 10
//#define COUNT 192
#define COUNT 4

Adafruit_NeoPixel pixels(COUNT, PIN, NEO_RGB + NEO_KHZ800);

void setup() {
  pixels.begin();
  pixels.setBrightness(100);
}

void loop() {
  for(int i = 0; i < COUNT; i++) {
    pixels.fill(pixels.Color(255,255,255), i, 1);
    pixels.show();
    delay(20);
    pixels.fill(pixels.Color(0,0,0), i, 1);  
    pixels.show();
    delay(20);
  }  
}