Retinal persistence on background's sprites when camera moves

Hello everyone,

I was working on my project, then i realized something strange going in the background.
In the video, you can see a retinal persistence (like a "white light") around the tall grass when the camera is moving.

I don't use any of the unity physics to move the player or the camera.
Camera is using LateUpdate.

If you have any clue why this is happening please let me know, i don't know where to search