Take control of the camera target texture and blit directly to it. This allows FSR2 upscaling to work on cameras that output to a target texture.

Packages/com.unity.postprocessing@3.2.2/PostProcessing/Runtime/PostProcessLayer.cs

@@ -216,6 +216,7 @@ namespace UnityEngine.Rendering.PostProcessing
 
         RenderTexture m_opaqueOnly;
         RenderTexture m_upscaledOutput;
+        RenderTexture m_originalTargetTexture;
 
         bool m_SettingsUpdateNeeded = true;
         bool m_IsRenderingInSceneView = false;
@@ -296,7 +297,20 @@ namespace UnityEngine.Rendering.PostProcessing
                 superResolution.ResetCameraViewport(m_CurrentContext);
                 
                 // Blit the upscaled image to the backbuffer
+                if (m_originalTargetTexture != null)
+                {
+                    Graphics.Blit(m_upscaledOutput, m_originalTargetTexture);
+                    RenderTexture.active = dst;
+
+                    // Put the original target texture back at the end of the frame
+                    m_Camera.targetTexture = m_originalTargetTexture;
+                    m_originalTargetTexture = null;
+                }
+                else
+                {
                     Graphics.Blit(m_upscaledOutput, dst);
+                }
+                
                 RenderTexture.ReleaseTemporary(m_upscaledOutput);
                 m_upscaledOutput = null;
                 return;
@@ -449,6 +463,16 @@ namespace UnityEngine.Rendering.PostProcessing
             volumeTrigger = transform;
         }
         
+        void LateUpdate()
+        {
+            // Temporarily take control of the camera's target texture, so that the upscaled output doesn't get clipped
+            if (m_Camera.targetTexture != null && m_CurrentContext.IsSuperResolutionActive())
+            {
+                m_originalTargetTexture = m_Camera.targetTexture;
+                m_Camera.targetTexture = null;
+            }
+        }
+
         void OnPreCull()
         {
             // Unused in scriptable render pipelines