Methods, systems, and devices for wireless communications are described. A base station may transmit a configured grant that indicates time-frequency resources for a user equipment (UE) to use to transmit sidelink or uplink messages in a wireless communications system. To reduce the amount of low priority traffic that may interfere with higher priority traffic, the base station may configure a threshold probability to allow high priority sidelink transmissions and to cancel low priority transmissions. The base station may transmit a cancellation indication that includes a priority indication instructing the UE to cancel transmissions having a priority less than a priority threshold during the allocated time-frequency resources. Based on transmitting the cancellation indication, the base station may cancel transmissions that have low priority, and the UE may determine whether to transmit (or to refrain from transmitting) one or more messages based on the priority of the message.