Lawyers getting caught using AI and submitting errors to the court has been a big problem for years
It wouldn't be a big problem if the unreliability of LLMs were part of ongoing professional development, use of LLMs without thorough fact checking was clearly barred by professional ethics, and lawyers were immediately disbarred for presenting false evidence if it came from an LLM.
It remains a "big" problem because it isn't big enough for anyone to do anything about it, beyond criticizing and ridiculing lawyers who do it.