Accessors, i.e. getters to be precise, returns a specific value. There are no constraints placed on what a getter can return.
However, in this case, the accessor seems to return an array that is a private
field.
In such cases, the returned array may be modified by the user as they are not write-protected.
Instead, it is recommended that you either not return an array or convert this property to a method and return a copy instead.
public int[] Buffer => _arr;
public int[] GetBuffer() => (int[]) _arr.Clone();