ESP8266-12, Random Neopixel flickering when using analogWrite()

[NoWayOut8344]

So as part of a bigger project im building Wifi Led Controllers using ESP8266-12 (not something like the node mcu just the esp), and im running into a problem where the Neopixels seem to flicker Randomly.

Some details:

• I'm controlling an (unadressable) 12V Led strip and the Neopixels in my Case fan (which are WS2812B's) with one Esp.

• The Esp sits on a developing/programming board (see picture) and is powered by the usb from my pc.

• I used 3 150 ohm resistors for the data line because i dont have any other suitable resistors at the time.

• The flickering seems to occur more often when i set the 12V strip to a dark brightness with 2 colors
  (aka like a dark purple or a dark yellow)
  When i set them to full brightness Red, Green, Blue or off, the Flickering is gone.

• When i comment out the code for the 12V Strip there also is no flickering.

• Everything exept the 12V is powered from my Pc.

• It doesnt seem to matter if i use the logic level shifter or not, and if i use the resistors or not the problem stays the same.

• After some time the Esp doesnt respond or looses connection and needs to be reset.

I've read that using PWM and the Neopixels at the same time on a esp can cause errors due to the strict timing of the pixels, but as far as i know the Adafruit NeoPixel Libary, which im using, disables interupts when pushing data to the Led's.

A Video displaying the problem:

Neopixel Flickering Problem

My Code:

#include <ESP8266WiFi.h>
#include <PubSubClient.h>
#include <Adafruit_NeoPixel.h>

Adafruit_NeoPixel pixels(20, 2, NEO_GRB + NEO_KHZ800);

WiFiClient wifiClient;
PubSubClient client(wifiClient);

byte r;
byte g;
byte b;
byte r2;
byte g2;
byte b2;
byte modus = 1;
byte circle = 0;

byte lastR, lastG, lastB = 0;
byte lastR2, lastG2, lastB2 = 0;

void callback(char* topic, byte* payload, unsigned int length) {
  r = payload[0];
  g = payload[1];
  b = payload[2];
  r2 = payload[3];
  g2 = payload[4];
  b2 = payload[5];
  modus = payload[6];
} 

void loadingCircle(byte red, byte green, byte blue) {
  noInterrupts();
  pixels.clear();
  for(int i = 0; i <= 20; ++i) {
    pixels.setPixelColor((i + circle) % 20, pixels.Color(red / 20 * i, green / 20 * i, blue / 20 * i));
  }
  ++circle;
  if(circle > 40) {
    circle = 0;
  }
  pixels.show();
  interrupts();
  delay(50);
}
void oneColor(byte red, byte green, byte blue) {
  if(red != lastR2 && green != lastG2 && blue != lastB2) {
    pixels.clear();
    for(int i = 0; i <= 20; ++i) {
      pixels.setPixelColor(i, pixels.Color(red, green, blue));
    }
    lastR2 = red;
    lastG2 = green;
    lastB2 = blue;
    pixels.show();
  }
}

void stripOutput(byte red, byte green, byte blue) {
  if(red != lastR && green != lastG && blue != lastB) {
    analogWrite(4, red);
    analogWrite(5, green);
    analogWrite(14, blue);
    lastR = red;
    lastG = green;
    lastB = blue;
  }
}

void setup() {
  analogWriteFreq(100);
  pinMode(4, OUTPUT);
  pinMode(5, OUTPUT);
  pinMode(14, OUTPUT);
  
  pixels.begin();
  
  WiFi.begin("Psalm_31.5", "GANZgeHeimer!");
  while (WiFi.status() != WL_CONNECTED) {
    pixels.clear();
    loadingCircle(240, 240, 240);
    stripOutput(6 * circle, 6 * circle, 6 * circle);
    pixels.show();
  }
  
  client.setServer("192.168.178.49",1883);
  client.setCallback(callback);
  while(!client.connect("esp1", "pc", "ledEnvironment")) {
    pixels.clear();
    loadingCircle(240, 40, 0);
    stripOutput(6 * circle, circle, 0);
    pixels.show();
  }
  
  for(int i = 0; i <= 20; ++i) {
    pixels.setPixelColor((i + circle + 1) % 20, pixels.Color(0, 255, 0));
    pixels.show();
    stripOutput(0, i * 12, 0);
    delay(30);
  }
  
  client.subscribe("led/pc");
  delay(970);
  pixels.clear();
  stripOutput(0, 0, 0);
  oneColor(0, 0, 0);
  pixels.show();
  delay(50);
  pixels.clear();
  stripOutput(0, 255, 0);
  oneColor(0, 255, 0);
  pixels.show();
  delay(100);
  pixels.clear();
  stripOutput(0, 0, 0);
  oneColor(0, 0, 0);
  pixels.show();
  delay(50);
  pixels.clear();
  stripOutput(0, 255, 0);
  oneColor(0, 255, 0);
  pixels.show();
  delay(100);
  pixels.clear();
  oneColor(0, 0, 0);
  stripOutput(0, 0, 0);
  pixels.show();
}

void loop() {
  switch(modus){
    case 1:
      oneColor(r2, g2, b2);
      stripOutput(r, g, b);
      break;
    case 2:
      loadingCircle(r2, g2, b2);
      stripOutput(r, g, b);
      break;
  }
  client.loop();
}

My Circuit:

The Programming/Developing board:

The logic level shifters:

Further Details:
The Esp gets the Color data from a MQTT-Broker on a raspberry pi 0 w. There i have a node red Ui to control the colors.

Anyway does somebody have any idea what could be causing this? Or are there any workarounds? (Preferrably software )
I have been searching the web but cant find any solutions.