What is the reason for J.P. Morgan changed his mind ?
i think you are confused about a meme.
what happened was starting from 2017 or maybe before he started talking negative about bitcoin and at some point he went as far as calling it "fraud" and he has been doing the same ever since without changing his stance. but at some point he also started praising the "technology" and build it up to their shitcoin which they recently revealed.
Yes, and this coin seems to be stable in value. From the overview about the coin understood it was an alternate to ripple, because it is developed in such a way to be functional on a centralized firm. This can be a way to turn people towards the largest financial network, this won't succeed as bitcoin is far away in growth.