Sforno on Deuteronomy 34:11/ספורנו על דברים ל״ד:י״א

1לכל האותות, the occasion when Moses experienced this type of communication from G’d described as פנים אל פנים occurred when he was called upon to perform the many supernatural miracles in Egypt. Clearly, his experience at the burning bush had not been of that calibre. Otherwise, why would the Torah have told us that he was afraid to look at the spectacle? (Exodus 3,6) This had been the very opposite of what G’d told Miriam and Aaron about his quality of prophecy in Numbers 12,8 i.e. that Moses can look without hesitation at visual images G’d shows him.