Also, lines of code is not completely meaningless metric. What one should measure is lines of code that is not verified by compiler. E.g., in C++ you cannot have unbalanced brackets or use incorrectly typed value, but you still may have off-by-one error.
Given all that, you can measure customer facing defect density and compare different tools, whether they are programming languages, IDEs or LLM-supported workflow.
Comparing lines of code can be meaningful, mostly if you can keep a lot of other things constant, like coding style, developer experience, domain, tech stack. There are many style differences between LLM and human generated code, so that I expect 1000 lines of LLM code do a lot less than 1000 lines of human code, even in the exact same codebase.