TWO SOURCE OPTIONS. “The detection of anti-4He or heavier nuclei would point to the existence of primordial antimatter from the Big Bang nucleosynthesis, while heavier particles such as antimatter 12C would point to the existence of stellar nucleosynthesis, or dense lumps of antimatter at galactic scale.”
https://link.springer.com/content/pdf/10.1007/s10686-021-09708-w.pdf