When you install an update to PixInsight, it removes all files in its “bin” directory and replaces them with updated files. If you had performed the necessary steps to enable GPU acceleration, this means that the tensorflow.dll file (tensorflow.so on Linux) will also have been replaced with the default CPU-only version distributed with PixInsight.

To restore GPU acceleration, you’ll need to repeat the “Download and install the GPU-enabled TensorFlow library” step of the instructions.