Unexpected Scoring in Pronunciation Assessment for Low-Quality Audio

Question

I have an audio file with very low sound quality, and I can barely hear anything from it. However, when I upload it to a pronunciation assessment service, it still recognizes the transcript and provides an evaluation. The strange thing is that the service returns a medium score, even though I expected it to give the lowest score for audio of such poor quality.

Why does the pronunciation assessment service return a medium score for audio with such poor quality instead of the lowest score, as expected?

Link audio: https://drive.google.com/file/d/1gMmDLd_36G_TXnp07MpeZND4Lk_dHXry/view?usp=sharing