gif About the number of views of the video "one time"

I use Python and Pillow to make a GIF.If I play it, it goes back and forth, but is it like that?
For example, I think I made a video that ends by moving a figure one way from left to right (once) on the screen, but when I play it, I go from left to right and then come back from right to left to end the playback.

The loop argument is not configured (default).

Thank you for your answers and comments.

Actually, originally
https://note.nkmk.me/python-opencv-mosaic/
Create GIF animation that is slowly mosaic
I brought it from .

imgs+=imgs[-2::-1]+[Image.fromarray(src)]*5

imgs[0].save('data/temp/opencv_mosaic.gif',
             save_all=True, append_images=imgs[1:], optimize=False, duration=50)

That's what it looks like