Transformation(Movement) of background with increasing Speed

Hi, my assignment has a moving character and for this i have made the character walk at a particular location and i am trying to move the background.

Here the movement of the background is in increasing order for every millisec.

To make this background reflect in a sequential manner i have used prefab but i get an issue 1. sometimes the prefabs get overlapped on eachother. 2. sometimes the prefab are instantiated far away from each other

this issue i face because of the increasing speed

please can you help me with any logic or any other idea.

Note: i don't want to transform the camera