I've noticed it when I'm on my Linux system, any software using PulseAudio as the output works and I can control it. Even though my audio server is running PipeWire, it can still process PulseAudio API. But when the software uses PipeWire, deej cannot control the volume of the apps listed on config.yaml. This happened with few software like CS2 using the command -sdlaudiodriver pipewire and osu! lazer directly changing the output to PipeWire.
Not to mention that the repo hasn't been getting updates, anyone who is using Linux could face this issue without realizing it.