buttigieg also supported m4a at the start of his presidential campaign (very vaguely, as he did everything, to be sure). he also switched his position on decriminalizing unauthorized entry sometime between the first debate and today.
the fakeness of his, at least to me, isn't so much changing your mind, it's turning around and attacking the people that hold the same position you held 3-4 months ago. it seems pretty obvious to me that his campaign decided there was more of an opening trying to take moderate white voters from biden than there was trying to share very liberal white voters with warren. he adjusted his beliefs accordingly.