If I had to guess the codec isn't meant to handle this well. To me this looks like a codec that wins because it is optimized for one specific use case (when you

If I had to guess the codec isn't meant to handle this well. To me this looks like a codec that wins because it is optimized for one specific use case (when you need "quite ok" audio on a modern day platform. It could be that it handles slower sampling rates well, but I am not sure about the bits.