The first match on the biggest court at Roland Garros saw Aryna Sabalenka beat Marta Kostyuk but it also saw the crowd boo the latter player after the 'no handshake'.
It was pretty much known that Marta Kostyuk wasn't going to shake hands with Aryna Sabalenka and when it happened nobody really was surprised. Sabalenka herself was asked about the possibility of that and she said that she didn't mind and actually kind of understood why it happens. The crowd in Paris felt a certain way though as they booed Kostyuk for the gesture.
Apparent unsportsmanlike conduct
Ukranians haven't been shaking hands with Russians or Belarusians for a while now but the crowd in Paris doesn't like what they perceive as unsportmanslike conduct. They don't like players arguing with umpires and will boo them immediately. They didn't appreciate Kostyuk avoiding the handshake either and booed her twice. First when it happened and the second time when she was leaving the court.
She didn't expect it:
“I want to see people react to it in ten years when the war is over. I think they will not feel
really nice about what they did. What happened today, I have to
say I didn't expect it. I did not, but I have no reaction
to it. People should be honestly embarrassed, but this is not my call.”