ProfileGPU gives the total time while all rendering is done in sync mode. So if steam deck supports async, the actual rendering time of TSR should be lower. It should be able to hide the first 0.46ms before TSRRejectShading. In UE5.6 you can use Unreal Insight to connect from the kit directly with e.g., -tracehost=10.28.6.234 -trace=default. Now it should be able to present what is happening in both graphics and async queues.