You can’t identify a gameObject with a string like “Cube1”. A gameObject is a gameObject, and should normaly just be compared to other gameobjects to see if 2 gameObjects are refering to the same gameObject etc.
You should instead identify it with a name or tag like this:
if(collision.gameObject.name == “Cube1”)
OR
if(collision.gameObject.tag == “Cube1”)
(note that a tag isnt the same as the name of the object)