I hope there is a lot of text in languages other than English. As for example in my language (Polish) current SOTA models are very deffiecient. I have wondered why is that considering companies like (not at all)OpenAI claim to train on large datasets including in my language of interest. It turns out (and I learned this just yesterday) they used LLM translated English content that that used as other language training data. They used Azure translator which itself is a transformer model to generate content for gpt-3.5 for example. Also, I bet there is a lot of poorly machine translated content in their supposedly "original" data.
The result? You can use chatgpt to write you an email of any kind in English and you can copy/paste/send immediately. Try doing that in Polish... It will make sense, but the language used will use bad tone (too familiar in a business setting), bad words(words that exist, but no real person would use) and sentence layout that just plainly feels weird. I suspect this is even worse in many other languages.