Let me share because this was puzzling to me in the first place, although it is an edge case.
The current Materials Project database says the GGA energy of Au4Sb8 (mp-738) is corrected by -0.13 eV/atom.
However, I think this correction was not applied in previous versions.
I think this came from [this commit] (Fix doc of oxidation_state_guesses. Fixes #3867. · materialsproject/pymatgen@cc663cc · GitHub), which changes candidate oxidation states from Element.oxidation_states to Element.common_oxidation_states in Composition.get_oxidation_guesses.
Composition.get_oxidation_guesses is called from MaterialsProject2020Compatibility to get oxidation states for anion species, including Sb.
The previous pymatgen (<=2024.6.10) assigns a negative oxidation state for Au, and a positive one for Sb, which results in no anion correction.
The fixed version only assigns a positive oxidation state for Au and is now negative for Sb, which results in artificial anion correction.
Scripts
from importlib.metadata import version
print(f'pymatgen: {version('pymatgen')}')
from pymatgen.core import Composition
c = Composition('Au4Sb8')
print(c._get_oxi_state_guesses(all_oxi_states=False, max_sites=-20, oxi_states_override=None, target_charge=0))
pymatgen: 2024.7.18
(({'Au': 3.0, 'Sb': -1.5},), ({'Au': (3,), 'Sb': (-2, -1)},))
pymatgen: 2024.6.10
(({'Au': -1.0, 'Sb': 0.5}, {'Au': 5.0, 'Sb': -2.5}, {'Au': 3.0, 'Sb': -1.5}, {'Au': 2.0, 'Sb': -1.0}), ({'Au': (-1,), 'Sb': (-2, 3)}, {'Au': (5,), 'Sb': (-2, -3)}, {'Au': (3,), 'Sb': (-2, -1)}, {'Au': (2,), 'Sb': (-1, -1)}))