I have a nuanced position on this, and I'm not claiming it is the correct one but I'll toss it in to see if it resonates. I don't think the three code violations came from a sexist place at all. Rules were broken, penalties were handed out. Unless one is heavily invested in the sexism/racism narrative and is specifically looking to generate clicks, sell media or take an opportunity to virtue signal I think most reasonable people can reach the correct conclusion that it was a game of tennis, rules were broken and enforced.
However I don't necessarily think Williams needs be dragged over the hot coals for this in the court of public opinion. High level sporting achievement requires tenacity, grit and passion. Sometimes tempers will flair it's only human. I also feel sexism/racism are still a problem and I think any woman or person of colour can be forgiven whenever that nagging doubt occurs in the back of their heads "Is this or that situation I'm in entirely fair or is this sexism or racism?"
Performing on the spot complex social analysis whilst trying to play a bloody game of high level tennis is a bit much, and this standard of expecting women and persons of colour to get it right every time is unrealistic, and accusing Williams of playing the woman or race card is unhelpful. We should live in and encourage an environment where people feel they can ask the question is this or that sexist or racist? And we should all try to puzzle through wether it is or not, and not be so quick to pile on if we then decide that it most likely isn't.
That said accusing anyone of racism/sexism is pointing a pretty big finger and the consequences of such accusations shouldn't just be collateral damage in the fight against bigotry, and in fact serves to do little else aside from pushing people into their own particular ideological corners, where people stop really communicating. I don't see anything that leads me to believe this Umpire was doing anything other than his job, I may be wrong and I'm willing to accept the consequences if I am making that error.