I suspect much of this has to do with the masks-—that when you cannot see people’s full faces, they are dehumanized, but so are you.
I guarantee you that the sunglasses that I was wearing long before the pandemic are far more "dehumanizing" than a mask, yet no one has a problem with sunglasses. It is the eyes that are the window to the soul.
Japan's problems can be traced back to the end of WWII. As in Europe Japan's toughest men were killed off in the war, leaving behind a pool of less vigorous specimens. Add that to a culture that prefers no social interaction at all over any kind of awkwardness and you get today's Japanese.
Take a look at the research starting to come out.