Antonyms for the phrase "what is coming to one" might include undeserved, unearned, or misdirected. When we say that someone is getting what they deserve, we imply that their actions or behavior have led to a predictable outcome. However, in some contexts, it may be more appropriate to suggest that someone is being treated unfairly or unjustly. For example, if someone is accused of a crime they did not commit and is punished for it, we might say that they are receiving something that is not coming to them. Similarly, if someone is rewarded for behavior that is unethical or harmful, we might say that they are receiving something that is misdirected.