Just like our preference for using "te" (even with "você" conjugations), we also have a preference for "tu" imperatives.
The "você" imperatives sound more formal. (Different from indicative uses use of "tu" and "você" where "tu" migth sound more elaborated).
But it's also regional.
Northeastern states tend to use more "lhe" (even as direct objects, bad grammar) and "você" imperatives. And, curiously, they tend to use "tu" indicatives.
Hahaha, we do mix things around here, don't we?
Frayah and Frayee
Perhaps the sounding of "Frayah" is also more emphatic. "Frayee" sounds weak, it lacks power at the end in the "yee" part. It gets unclear for such an emergential command.
You're right about mixing things up. :-) Certainly Duolingo can't make its mind up because it says "Brake!" using "Freia!" (tu) and "Stop!" with "Pare!" (você): https://www.duolingo.com/comment/6086287
The reason I was confused about the pronunciation of "Freie!" was that I used the Ivona demo: https://www.ivona.com/ to hear it spoken and the female says "Frayee" but the male appears to drop the "ee". Thanks for sorting that out.
Wasn't that in the imperatives lesson? At first the English version was Brake! but there were user comments that nobody ever says that, so it got changed to Stop! Always a difficult choice between literal translations that make no sense in English, or proper English that gets in the way of learning Portuguese.