Got rid of the global callbacks thing and made callbacks a local field of the Fsr2ImageEffect script.

This way different applications of FSR2 within the same game can have different callbacks applied to them.
For example: a camera for rendering a 3D UI image to a render texture can have callbacks to apply mipmap bias only to the assets being drawn for the UI.

Assets/Scripts/Core/Fsr2.cs

@@ -30,13 +30,10 @@ namespace FidelityFX
     /// </summary>
     public static class Fsr2
     {
-        // Allow overriding of certain Unity resource management behaviors by the programmer 
-        public static IFsr2Callbacks GlobalCallbacks { get; set; } = new Fsr2CallbacksBase();
-
         /// <summary>
         /// Creates a new FSR2 context with standard parameters that are appropriate for the current platform. 
         /// </summary>
-        public static Fsr2Context CreateContext(Vector2Int displaySize, Vector2Int maxRenderSize, InitializationFlags flags = 0)
+        public static Fsr2Context CreateContext(Vector2Int displaySize, Vector2Int maxRenderSize, IFsr2Callbacks callbacks, InitializationFlags flags = 0)
         {
             if (SystemInfo.usesReversedZBuffer)
                 flags |= InitializationFlags.EnableDepthInverted;
@@ -54,7 +51,7 @@ namespace FidelityFX
                 Flags = flags,
                 DisplaySize = displaySize,
                 MaxRenderSize = maxRenderSize,
-                Callbacks = GlobalCallbacks,
+                Callbacks = callbacks,
             };
             
             var context = new Fsr2Context();

Assets/Scripts/Fsr2ImageEffect.cs

@@ -34,6 +34,8 @@ namespace FidelityFX
     [RequireComponent(typeof(Camera))]
     public class Fsr2ImageEffect : MonoBehaviour
     {
+        public IFsr2Callbacks Callbacks = new Fsr2CallbacksBase();
+        
         public Fsr2.QualityMode qualityMode = Fsr2.QualityMode.Quality;
 
         public bool performSharpenPass = true;
@@ -109,7 +111,7 @@ namespace FidelityFX
             
             // Apply a mipmap bias so that textures retain their sharpness
             float biasOffset = Fsr2.GetMipmapBiasOffset(_renderSize.x, _displaySize.x);
-            Fsr2.GlobalCallbacks.ApplyMipmapBias(biasOffset);
+            Callbacks.ApplyMipmapBias(biasOffset);
             
             if (!SystemInfo.supportsComputeShaders)
             {
@@ -126,7 +128,7 @@ namespace FidelityFX
             if (enableFP16) flags |= Fsr2.InitializationFlags.EnableFP16Usage;
             if (enableAutoExposure) flags |= Fsr2.InitializationFlags.EnableAutoExposure;
 
-            _context = Fsr2.CreateContext(_displaySize, _renderSize, flags);
+            _context = Fsr2.CreateContext(_displaySize, _renderSize, Callbacks, flags);
 
             _dispatchCommandBuffer = new CommandBuffer { name = "FSR2 Dispatch" };
 
@@ -151,7 +153,7 @@ namespace FidelityFX
         {
             // Undo the current mipmap bias offset
             float biasOffset = Fsr2.GetMipmapBiasOffset(_renderSize.x, _prevDisplaySize.x);
-            Fsr2.GlobalCallbacks.ApplyMipmapBias(-biasOffset);
+            Callbacks.ApplyMipmapBias(-biasOffset);
             
             // Restore the camera's original state
             _renderCamera.depthTextureMode = _originalDepthTextureMode;

Assets/Scripts/Fsr2PostProcessEffect.cs

@@ -190,15 +190,11 @@ namespace FidelityFX
             if (settings.enableFP16) flags |= Fsr2.InitializationFlags.EnableFP16Usage;
             if (settings.enableAutoExposure) flags |= Fsr2.InitializationFlags.EnableAutoExposure;
 
-#if UNITY_EDITOR || DEVELOPMENT_BUILD
-            flags |= Fsr2.InitializationFlags.EnableDebugChecking;
-#endif
-            
-            _fsrContext = Fsr2.CreateContext(DisplaySize, RenderSize, flags);
+            _fsrContext = Fsr2.CreateContext(DisplaySize, RenderSize, null, flags);
 
             // Apply a mipmap bias so that textures retain their sharpness
             float biasOffset = Fsr2.GetMipmapBiasOffset(RenderSize.x, DisplaySize.x);
-            Fsr2.GlobalCallbacks.ApplyMipmapBias(biasOffset);
+            //Fsr2.GlobalCallbacks.ApplyMipmapBias(biasOffset);
         }
         
         private void DestroyFsrContext()
@@ -210,7 +206,7 @@ namespace FidelityFX
                 
                 // Undo the previous mipmap bias adjustment
                 float biasOffset = Fsr2.GetMipmapBiasOffset(RenderSize.x, _prevDisplaySize.x);
-                Fsr2.GlobalCallbacks.ApplyMipmapBias(-biasOffset);
+                //Fsr2.GlobalCallbacks.ApplyMipmapBias(-biasOffset);
             }
         }