Not understanding slice length and capacity
A slice is an array that can grow or shrink in size. In Go, a slice is backed by an array, and handles the logic of adding new elements if the backing array is full or shrinking it if it is almost empty.
Internally, a slice holds a pointer to the backing array and keeps track of a length and capacity. The length is the number of elements the slice contains, while the capacity is the number of elements in the backing array.
Mistake
When slicing an existing slice, both slice pointers will be referencing the same array. This can cause unexpected behavior if one of the slices alters its data, that alteration will also be reflected in the other slice.
Fix
Initialize a separate slice and populate it using append.