When you use the Object offset, what’s happening is that Blender is going to use the relation between your original object and your Empty as a “first step” mesure.
In other words, your Empty equals your first array copy.
So in this case if you scale the original object and leave the Empty as default, your Empty is smaller than the origin object therefor it means that your first array step is smaller and as you go further in the array, you keep applying the ratio transform that there is from the origin-object to the Empty and you end up going smaller and smaller.
Hope this explanation is clear ^^’
