In spring 2021, during the COVID-19 pandemic, research projects funded by the UK’s Global Challenges Research Fund (GCRF) were subjected to budget cuts. The cuts were the result of UK government’s decision to reduce its Official Development Assistance (ODA), which had devastating effects for humanitarian, development and research work. This article draws on focus group discussions with project teams working on three large GCRF-funded projects to explore the effects of these cuts. The article documents how the cuts curtailed project aspirations and impact, had a negative toll on the mental health of researchers, and imperilled the trusting relationships upon which international research collaborations are built. The article argues that the cuts expose the shallow commitments to research ethics and equitable partnerships of powerful actors in the UK research ecosystem, including research councils and government. In ‘doing harm’ via these cuts, the article explores the failure of research governance structures and the continued coloniality underpinning the UK’s approach to researching ‘global challenges’.