It’s a model-related issue. I think its unlikely Microsoft would have a fix, yet OpenAI users would be stuck.
You can go back to 0613 versions and not solicit (nor receive) parallel tool calls (with its smaller context length and better overall quality). Imagine it’s October.
The arguments dumping a whole bunch of newline (either escaped or the code) can be the forced json-mode of functions. You can specify “valid json” all over the function description and system message to reduce the chance of this, but the behavior is still brought out strong in high-UTF8 or Unicode characters, even on later json substrings after English.
Attempts to improve garbage function outs: