python 3.10 "os.system" command kills tkinter GUI

Question

While I figured this out by myself, I am stuck with another problem.

As soon as os.system("taskkill /PID " + p.decode('UTF-8')[-8:].lstrip()) gets executed, the tkinter GUI gets shutdown. The actual issue might be called earlier during creation of a subprocess.

def reconn():
    global connected
    global s
    p = subprocess.Popen("netstat -a -n -o |find \"" + HOST + ":" + str(PORT) + "\"", shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE).communicate()[0]
    os.system("taskkill /PID " + p.decode('UTF-8')[-8:].lstrip())
    showGUI()
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    connected = False

the showGUI() function simply reopens the GUI, which wouldn't be necessary if it won't close in the first place.

Check out the link for the full code.