I notice this especially with my Norwegian learning. People are rude, call me names, or make fun of me on Reddit for using the wrong word or “en” vs “et” or using a direct translation because I don’t know how they say it in Norwegian, like saying somethng like «Ingen av bedriften din!» instead of «Dette er ikke din sak» (according to the casual version of Bing Translate) whereas a Norwegian-speaking Fediverse member would just say something like “You’re doing good, but it’s actually _____.”
Not disagreeing with the other comments here but I’d add that hostility breeds engagement, and for sites like Reddit, engagement equals more time spent on the site and more opportunities to serve ads.
Whether intentional or not, the algorithms push more aggressive/rude/hurtful comments to the top. Reddits business is making money off you while lemmy is just there. I expect that accounts for some of what you see