I don't think he changed, it's just that i-land was way too stressful for everyone, you can see that in enhypen boys too, since they know their debut is really happening they can show now how they are without so much pressure and enjoy a little more, that's how I see at least haha
K was actually like this back then too. He opened up a lot after there were only 10 ilanders left in Iland part 2. That's when we got to see a bit more free side of K. Also mnet had this weird obsession with showing only his tense sides. Back then who were watching iland live watched iland cams too where ee actually got hold of how bubbly of a person he is.
He has been like this since day 1, u can literally see in behind cams of iland too. But people really love mnet's editing and fall for it every single time even after saying it's bad. Fucking hypocrites.