@dalke here's another example where this affects the match count on even a relatively small molecule
mol = Chem.MolFromSmiles("FS(F)(F)(F)(F)N(S(F)(F)(F)(F)(F))S(F)(F)(F)(F)(F)")
pat = Chem.MolFromSmarts("[$([d6](*)(*)(*)(*)(*)*)]")
print(len(mol.GetSubstructMatches(pat)))
only 2 matches! (the N(SF5)3 molecule actually exists: https://doi.org/10.1016/j.molstruc.2016.05.089 )