”—“Is what is impermanent, suffering, and subject to change fit to be regarded thus: ‘This is mine, this I am, this is my self’?”—“No, venerable sir.”
Yaṃ panāniccaṃ, dukkhaṃ vipariṇāmadhammaṃ, kallaṃ nu taṃ samanupassituṃ 'etaṃ mama, eso’hamasmi, eso me attā’ti? No hetaṃ bhante. SN22.59
So it seems that impermanence is the cause for non-belonging, according to SN22.59. They seem to be distinct concepts, depicted as cause and effect, one arising first and then giving rise to the next.
It may be that belonging is a key feature of atta, in Vedic or Brahmanical thinking (or the opposite of it). I noticed that a video of Advaita philosophy also used ‘non-belonging’ to delineate what wasn’t (true) Self. But to think of the Buddhist flavour of the use of these concepts, non-belonging doesn’t feature prominently, though it is part of it and @suci1 might want to explore its implications further.
with metta