I think it should be an expectation to do better.. I would support someone trying to do better and calmly explain mistakes. Its a hard thing to question core beliefs you learned no matter how fucked or dysfunctional. It creates lots of discomfort like most personal growth and its really fantastic when folks choose to confront that discomfort to make the world a little nicer for others.
This being said, I'm white.. these comments don't dehumanize and devalue me. This means I have the space to be calm and correct someone. It means if I don't say something to other white folks that I'm part of the problem. I feel like EVERYONE has the responsibility to unlearn/call-out toxic shit until we die.
POC on the other hand don't need to extend that courtesy/kindness because its harmful to their wellbeing. POC don't owe you explanations or their help to "do better". If POC corrected every racist thing someone said im sure it would take up a massive portion (if not all) of their day and be exausting. Plus POC don't need to like or involve ppl in their lives who (even unintentionally) hurt them or make them feel like shit all the time.
I'm queer so although its not the same and I have the option of living in the closet (something poc can't do) I find existing is sometimes VERY tiring even though I get the option to take a break sometimes. I appreciate that people are trying to learn and do better. I really do think it's wonderful and its very hard... but I do need someone to have a certain level of understanding and appropriate behaviors to want them in my life, otherwise they are toxic and I cut them off or limit contact for my own wellbeing; no it doesn't matter "if they are trying". Intention is less important than outcome when it directly affects my wellbeing. They are welcome back when they are doing better and understand some of the pain they've caused.. not looking for perfection but looking the bare minimum it takes to not affect my mental health or make me feel like shit all the time. I think its a pretty fair line to have.