detractive

/dɪˈtræktɪv/
adjective
  1. Tending to lessen the value, reputation, or importance of something; critical or disparaging.
    • Instead of offering helpful feedback, he made only detractive statements.
    • The article was full of detractive remarks that didn't reflect the charity's real impact.
    • Her detractive comments about the project made the team feel discouraged.