If you can't detail why it's bad in any shorter form than a 90 minutes video, perhaps it's not that bad.
"And so, while I overall very much enjoyed my time there and have freely recommended it to many people, the decision to pursue a PhD in Japan should always be considered carefully."
literally sounds like "as an AI model..." type of disclaimer or padding
like, who isn't going to carefully consider on how/where to do their PhD?
Perhaps it is the contrast of "freely recommending" and "always should be considered carefully"?
Or taking a larger leap: the awkwardness of saying how hard (isolating) it is to do a PhD in an unfamiliar country, then saying that you enjoyed it, but others should consider it carefully?