Devices and methods for managing congestion notifications for Low Latency, Low Loss, and Scalable throughput (L4S) data flows are provided. A device receives a downstream data flow including multiple downstream data packets and identifies one or more downstream L4S data packets therefrom. The device stores the downstream L4S data packet(s) in a queue and detects a congestion in downstream based on the queue. The device transmits, at a lower protocol layer, an indication of the congestion to a wireless device that is a destination of the downstream L4S data packet(s). The wireless device marks at least one downstream L4S data packet with a congestion indicator based on the indication of the congestion. Such congestion indication provides a fast congestion notification associated with the L4S data flows to facilitate a fast response to the congestion and a reduction of congestion-related packet drops at the device.