On 2 February 2022, the Belgian Data Protection Authority handed down a decision concerning IAB Europe and its Transparency and Consent Framework (TCF), a system designed to facilitate compliance of real-time bidding (RTB), a widespread online advertising approach, with the GDPR. Here, we summarise and analyse this large, complex case. We argue that by characterising IAB Europe as a joint controller with RTB actors, this important decision gives DPAs an agreed-upon blueprint to deal with a structurally difficult enforcement challenge. Furthermore, under the DPA’s simple-looking remedial orders are deep technical and organisational tensions. We analyse these “impossible asks”, concluding that absent a fundamental change to RTB, IAB Europe will be unable to adapt the TCF to bring RTB into compliance with the decision.