public static IEnumerable<byte[]> Split(byte[] array, byte[] separator)
        {
            if (array == null) throw new ArgumentNullException(nameof(array));
            if (separator == null) throw new ArgumentNullException(nameof(separator));
            if (separator.Length == 0)
                throw new ArgumentException("Value cannot be an empty collection.", nameof(separator));

            var lastIndex = 0;

            for (int i = 0, j = 0; i < array.Length; ++i)
            {
                if (array[i] == separator[j])
                {
                    if (++j < separator.Length) continue;
                    yield return SubArray((i - separator.Length + 1) - lastIndex);
                    lastIndex = i + 1;
                }
                j = 0;
            }

            yield return SubArray(array.Length - lastIndex);

            byte[] SubArray(int length)
            {
                if (length == 0) return Array.Empty<byte>();
                var span = new byte[length];
                Array.Copy(array, lastIndex, span, 0, length);
                return span;
            }
        }

Split(separator: [8, 21], array: [])
[[]]
Split(separator: [8, 21], array: [1])
[[1]]
Split(separator: [8, 21], array: [1, 2, 3])
[[1, 2, 3]]
Split(separator: [8, 21], array: [8])
[[8]]
Split(separator: [8, 21], array: [21])
[[21]]
Split(separator: [8, 21], array: [8, 21])
[[], []]
Split(separator: [8, 21], array: [8, 21, 8, 21, 8, 21])
[[], [], [], []]
Split(separator: [8, 21], array: [1, 8, 21])
[[1], []]
Split(separator: [8, 21], array: [8, 21, 2])
[[], [2]]
Split(separator: [8, 21], array: [1, 8, 21, 2, 8, 21, 3])
[[1], [2], [3]]
Split(separator: [8, 21], array: [1, 2, 3, 8, 21, 2, 3, 4, 8, 21, 3, 4, 5])
[[1, 2, 3], [2, 3, 4], [3, 4, 5]]

stringValue.Split(new char[] { '','' });