It's clear that Serena has been on the end of a significant amount of discrimination over the years she has been in tennis (and before). As a woman and as a black person.
I believe that the announcement from Roland Garros about her not being allowed to wear the clothing she wore this year (to protect herself from medical difficulties as a result of her C section)is an example of her being discriminated against.
Likewise, her losing her ranking points because of pregnancy (she would have kept them if injured) is a failure of the tour.
There are also many clear examples of other woman tennis players being discriminated against, eg the penalty given to the woman who switched the top around on court because it was back to front.
However, there are times when Serena (as with everyone else) is in the wrong, and when she cries discrimination at those times, it undermines her argument.
It feels a little like in fighting agains tthe discrimination she has received, she sometimes views legitimate rules as just another thing that is attacking her.
This umpire followed the rules correctly. He could have turned a blind eye, he could have bent the rules due to the situation and the person, but that is bad law, and he has a record of applying the letter of it. He has warned Murray for saying "Stupid umpiring" for example (and that's way less important than calling him a thief and a liar). Serena should not have destroyed her raquet when she had already received a warning, and she should not have called him a thief. Many football referees are guilty of reffing the context rather than the game in front of them, and it is bad for the game (the most common example is that if you commit a red card challenge in the first few minutes you are enormously unlikely to get sent off). I give credit to the umpire in this case for applying the rules, rather than letting it go because it's a final (or because it's Serena).
Serena has also complained about the application of drug testing protocol before, in particular when a tester turned up at her house and she went into her panic room and refused to do the test. Somehow, that ended up being a whereabouts failure rather than a refusal (which carries an automatic ban). She then claimed that the frequency of her out of competition tests were discrimination, when the rules are explicit increasing frequency on an athlete who has been out of competition for an extended period and then returns (especially in cases where prior biological passport values are now no longer usable.
In both these cases, she has used her clout as a superstar to get the people at the top of the relevant organisation to back her (the tournament organiser, and the head of USADA), and to get the people who were applying the rules into trouble, rather than doing anything about the rules that were being applied.