I think (outside hobbies) new programming language development is basically dead at this point. The major use cases have been filled, and there are more forces than ever towards using a battle-tested language with a massive ecosystem. Further, less and less code is being written or read by humans so the actual language ergonomics matter less than ever to those who would fund new language creation.
For gamedev scripting, the gap has not been filled yet. Lua is good for embedding but the language itself is terrible for LLM usage (too much dynamic typing). C# is too heavy for scripting usage (long compile times, clunky to embed into a C++ engine), and other alternatives (AngelScript, daScript, ...) are just too niche.
What about Python? LLMs seem to like it well enough.