This is the standard that most of producers work on. In these type of projects the base is original from the producer — chords, melodies, leads, etc — but it contains additional melodic elements that complement the track and come from royalty-free sample packs. They are usually vocal chops, real instrument chords or textures, wobbles basses, glitch effects, etc. In a project file of this category you will find MIDI files created by the producer, but also melodic loops
Made by Serum, Sylenth, Spire, the arp loop from the description is used only for ambient purposes, everything else is original.
Sample pack MHA atmos
Loop name MHA Atmos - Arp 12 B_126BPM