VLC module for python, video not always start fullscreen

Question

for a project on a Rpi I need a video to be played fullscreen. I was used to work with Omxplayer but as being deprecated I need now to use VLC. Sadly the video randomly start in a separate windows instead of starting fullscreen. Here is a part os the code. Any ideas how I should solve this?

from gpiozero import Button, LED
import vlc
import time

# Define GPIO pins for buttons and LEDs
GPI_1_PIN = 2
GPI_4_PIN = 4
GPO_2_PIN = 17
GPO_3_PIN = 27
GPO_5_PIN = 22
GPO_6_PIN = 23

# Set up Buttons and LEDs
button_1 = Button(GPI_1_PIN)
button_4 = Button(GPI_4_PIN)
led_2 = LED(GPO_2_PIN)
led_3 = LED(GPO_3_PIN)
led_5 = LED(GPO_5_PIN)
led_6 = LED(GPO_6_PIN)




# Variable to track button states
button_1_pressed = False
button_4_pressed = False

vlc_instance = vlc.Instance("--no-xlib")
player = vlc_instance.media_player_new()

# Function to play video
def play_video(video_path):
 

    # Stop the currently playing video
    player.stop()
    media = vlc_instance.media_new(video_path)
    media.get_mrl()  # To get rid of VLC warnings
    player.set_media(media)
    time.sleep(1.1)
    player.set_fullscreen(True)
    player.play()
 
def display_photo(photo_path):
    player.stop()
    media = vlc_instance.media_new(photo_path)
    media.get_mrl()  # To get rid of VLC warnings
    player.set_media(media)
    time.sleep(1)
    player.set_fullscreen(True)
    player.play()

# Display the photo before entering the main loop
display_photo("video1.mp4")

    

# Main loop
try:
    while True:

        # Check if GPI_1 button is pressed
        if button_1.is_pressed and not button_1_pressed:
            button_1_pressed = True
            player.stop()
            time.sleep(0.5)
            vlc_instance.release()
            vlc_instance = vlc.Instance("--no-xlib")
            player = vlc_instance.media_player_new()
            play_video("video1.mp4")
            led_2.on()
            led_3.on()
            time.sleep(0.1)
            led_2.off()
            led_3.off()
            

        # Check if GPI_1 button is released
        elif not button_1.is_pressed and button_1_pressed:
            button_1_pressed = False

        # Check if GPI_4 button is pressed
        if button_4.is_pressed and not button_4_pressed:
            button_4_pressed = True
            led_5.on()
            led_6.on()
            time.sleep(0.1)
            led_5.off()
            led_6.off()
            player.stop()
            time.sleep(0.5)
            vlc_instance.release()
            vlc_instance = vlc.Instance("--no-xlib")
            time.sleep(0.5)
            player = vlc_instance.media_player_new()
            play_video("video2.mov")
        

        # Check if GPI_4 button is released
        elif not button_4.is_pressed and button_4_pressed:
            button_4_pressed = False
        
        if player.get_state() == vlc.State.Ended:
            player.stop()
            player.set_position(0)
            player.play()

except KeyboardInterrupt:
    pass

finally:
    player.release()
    vlc_instance.release()

Is there a way to make the video ALWAYS start fullscreen?