That review is saying exactly what I saying from the very beginning of this thread 5 months ago about the difference in sound quality between active and fully passive modes.
BUT, for me the more important thing is that, after 5 months with sufficient 'reviews' published, this is really this first 'review' that is more honest/correct about the real (immediately noticeable!) differences between full passive and active modes. This is one reason why (in the case of the iO-12, like so many others headphones) the majority of 'reviews', for me, are not good, are mediocre or are simply not very professional.
By the way, for me, in difference with that review (from Hungary), the USB-C mode and BT mode are practically identical. The writer, in my view, is wanting to believe that, because you're using a (USB-C) cable connection, the sound is even better. Not true for me, and in blind test I'm sure the majority of people will not knowing if is BT or USB-C mode.
(I like the photo that you posting!)