Just an update: I’ve confirmed that this issue is fixed in iOS 27. MTL4FXTemporalDenoisedScaler now initializes successfully. Thank you!

Thank you.I posted the feedback. FB22575333

Thanks for the clarification. On my iPhone 15 Pro (A17 Pro), MTLFXTemporalDenoisedScalerDescriptor.supportsMetal4FX(device) actually returns true. In other words, because supportsMetal4FX(device) returns true on iPhone 15 Pro, I have no way to avoid taking the Metal 4 FX code path.