Having a clear and stable sense of how one performs in a field is a key contributor to goal pursuit. Performance feedback is often considered a crucial resource for developing this clear and stable self-knowledge but may be less optimally integrated when feedback is considered inaccurate or dishonest. The current paper investigates how such feedback perceptions may limit the development of people's ability self-concept, and how workplace contexts can restrict communication. A 2-week daily diary study among 197 junior researchers working in STEM-fields (N = 1,353 data points) showed that those in more competitive (vs. more collaborative) work environments overall perceived feedback as more inaccurate and dishonest (but not as more positively inflated). These results did not differ for men and women, showing that both face negative consequences of working in a more competitive context in terms of their ability to get high-quality feedback. On the daily level, results showed that days on which people received more inaccurate and dishonest (but not positively inflated) feedback were also days on which they reported higher imposter feelings, and lower ability self-esteem, self-concept clarity, and self-concept stability. In turn, days on which people felt more like an imposter and reported lower ability self-esteem, self-concept clarity, and self-concept stability, were also days on which motivation was lower. Ability self-esteem and self-concept clarity (but not imposter feelings and self-concept stability) were also related to lower daily risk-taking tendencies. Together, these results show that an important contextual factor--the perceived competitiveness of one's work environment--influences feedback inaccuracy and dishonesty, with consequences for the ability to develop a clear, stable and certain ability self-concept.