Hey @leonard-IMBERT this is a case where automatic symmetry determination is very sensitive to the tolerances used. Changing the linear distance tolerance used to identify the space group changes it drastically:
from mp_api.client import MPRester
s = MPRester().get_structure_by_material_id("mp-22730")
for symprec in (0.01, 0.1):
print(symprec,s.get_space_group_info(symprec=symprec))
>>> 0.01 ('C2/c', 15)
>>> 0.1 ('Fddd', 70)
Also keep in mind that the MP structure can be any repeat unit of the primitive cell. If we transform the structure to its conventional representation, the symmetry is more apparent:
conv = s.to_conventional(symprec=0.1)
print(conv.lattice.abc)
print(conv.lattice.angles)
>>> (6.349580320450959, 10.286833706850889, 12.638767248826353)
>>> (90.0, 90.0, 90.0)