Abstract Potential contribution from gamma-ray sources to the Galactic diffuse gamma rays observed above 100 TeV (sub-PeV energy range) by the Tibet AS γ experiment is an important key to interpreting recent multimessenger observations. This paper reveals a surprising fact: none of the 23 Tibet AS γ diffuse gamma-ray events above 398 TeV within the Galactic latitudinal range of ∣ b ∣ < 10° come from the 43 sub-PeV gamma-ray sources reported in the 1LHAASO catalog, which proves that these sources are not the origins of the Tibet AS γ diffuse gamma-ray events. No positional overlap between the Tibet AS γ diffuse gamma-ray events and the sub-PeV LHAASO sources currently supports the diffusive nature of the Tibet AS γ diffuse gamma-ray events, although their potential origin in the gamma-ray sources yet unresolved in the sub-PeV energy range cannot be ruled out.