Not a bug.
Okoye starts with lots of buffs, SS removes and deals damage for every buff on fight start.
You're not doing right by your username
Never bring in a champ with buffs against Symbiote Supreme. LIke @phillgreen said, he removes them and deals damage for each buff. Okoye starts with like 15 precision buffs and they get removed at the start of the fight so that is why you died instantly. Also don't use her against Nico, you will get poison to death.