[BUG] DeepSeek sometimes responds in Chinese, even when the chat is in English

Bug Description: If you start a chat with DeepSeek in English (first prompt and all other prompts are in English), sometimes, the model will generate a response in Chinese. Usually, both the Think window and the response are in Chinese. Sometimes, only the Think text is in Chinese, while the response is in English. Most of the time when the bug occurs, both Think text and the response are in Chinese. When it happens, you must say "respond in English" or something along the lines in order for the model to generate an English response. The bug can also occur multiple times in a row, so you get a Chinese response again after each English response you got after telling the model to respond in English.

Additional context: Before the unification of Instant, Expert and Vision into a single model, only Instant was prone to the bug when the Search feature was enabled and Think mode wasn't, meanwhile, Expert and Vision never produced that bug. Currently, with the unified model, the bug happens when Think and Search modes are enabled, too.

How to reproduce the bug: Just have a chat in English, keep chatting, and the bug will eventually appear. It happens on its own, there is no specific word or sentence wording that triggers it.

Expected behaviour: The model should always produce responses in the same language the prompts are in, unless explicitly asked to respond in a different language.

Screenshots: No. If needed, I will upload them in a different thread.