Christian hermeneutics said both
Please read what I wrote. Jer. 28:5 has יִרְמְיָה (Yirme*yah*) and Jer. 7:1 has יִרְמְיָהוּ (Yirme*yahu*). As for your former comment, yes, that should have been the case, but that's not what happened. That's why there is no transliteration of the Tetragrammaton in the Septuagint. Ever.
They both refer to the same guy I suppose. Yet in some verse it's written as Yirmeyah and and some other verse it's written as Yirmeyahu.
Which one is right?
The prophet change his name?