Two countries [US & Israel] booed at Olympics opening ceremony despite stern warning
(www.independent.co.uk)
They weren't banned for the Ukraine thing, but for doping. There are Russian athletes that compete under ROC in Olympics now.
Edit-well, looks like I was wrong. The ban was rescinded in '22, than there were banned again for the Ukraine invasion. And now some athletes compete under AIN, Athletes from Individual Neutral Athletes