My understanding is that objects off screen isn’t rendered. It could be your events that are affecting it. Can you provide screen snips of any events that involve the block objects?
That terrain is being generated every single game frame - around 60 times per second. There are no conditions to stop it, so it’s continuously creating blocks.
Instead, you should look at generating the blocks as needed once you have a few screen full. Here’s an example of that, but only for filling in the right side as the camera moves right: