Robots struggle with syntax-in-syntax. Really easy to confuse them when asking it to write a SQL query that targets a JSON column but it must respond with a JSON envelope so the harness can parse the result. Lots of escaping that needs to happen. Deeply nested structures in JSON also end up with foibles like missing a ] or } in a string of }}]}]}. Aside from the prompt injection possibility, just the result being straight up broken and requiring another LLM call is tokens flushed.