meaning - "Mistaken as" vs. "mistaken for"

I heard someone use the words mistaken as rather than mistaken for.

Is this correct? If it is correct then what is the difference between the two? Is it ever wrong to use mistaken as, and if so, why?

I ask because I was recently advised about something:

It shouldn't in any way be mistaken as an academic judgement.

In dictionary definitions and usage guides, the preposition used is given as for, not as. However, there are other examples with as, such as ones in comments below, as well as in books on the internet.