Multiplicative Persistence #2
Husk, 10 bytes
►ȯLU¡oΠd↔ŀ

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Explanation
►ȯLU¡oΠd↔ŀ
        ↔ŀ reverse the range 0..n-1
►ȯ         max-by, returning the last maximal element for the following:
    ¡o      create an infinite list using:
      Πd     product of digits.
   U        longest unique prefix
  L         take its length