There has been a very interesting shift in how Japan is perceived at the very least online in the past 10 years. I remember during the 2010s when tourism in Japan picked up, everybody and their mom talked about Japan as this utopian wonderland with no faults. It was all anime, idols, nice people, beautiful nature and nobody in Japan could do wrong. And then sometime before the pandemic that view completely shifted to Japan being terrible. Shit work-life balance, high suicide rates, low birth rates, racist/xenophobic population who all just act nice but ultimately hate foreigners and a country with no future. This happens with many countries but especially Japan; people just really can not see that a country has it's good and bad sides. It's either all fantastic or all shit.
And that video is pretty good at calling out a specific group of people within Japan that have become bitter and cynical because of exactly what the "joke" was: they got there as ALTs, never progressed further, maybe got married to the first Japanese woman they met and are now hating life. They see other foreigners who recently started living in Japan and belittle them, tell them they'll hate it after a while too and that everything is shit in the hopes that it actually comes true so that they aren't the only miserable prick.