According to embodiments, a first UE (e.g., UE A) receives from a second UE (e.g., UE B) a sidelink control information (SCI) in a first slot. The SCI comprises a resource reservation for a shared channel. The resource reservation indicates a set of frequency resources and a time resource assignment. The first UE transmits to the second UE a conflict indicator on resources of a feedback channel. The resources of the feedback channel include a second slot for transmitting the conflict indicator. A location of the second slot is based on one of the first slot or a slot indicated by the time resource assignment. The conflict indicator indicates a potential resource conflict or a detected resource conflict on at least one of the set of frequency resources or the time resource assignment indicated by the resource reservation.