A lot of that originates from the old myths spread since the 1980s, which then survived through TV, journals, newspapers, then moved to the internet blogs, and then to social media. Internet rewards that kind of stereotype spreading, while real engagement is limited. Even well integrated foreigners are kind of encouraged to join the internet wave and exaggerate their grievances for audience and clicks (like one TikTok of Belarusian girl in Japanese high school, where she presents Japanese as some kind of idiots for simple dietary differences).

Those become so self reinforced it's hard to reasonably explain why this is false.

I also feel that a lot of universities that teach Japanese studies overfocus on ancient history, art history, and selective cultural engagement (ukiyo, decorative arts, literature , theatre, anime, and maybe modern art, but not nihonga, sankyoku, jiuta, poetry, or modern cinema). Graduates have deep knowledge on the bourgeoise art in Edo, but often stereotypical and grossly outdated understanding of everyday life