The jury is still out on that one.
Having a tool that’s embedded into your workflow and shows you how things can be done based on tons of example codebases could help a junior dev quite a lot to learn, not just to produce.
Like anything else with learning, that will be heavily dependent on the individual's level of motivation.
Based on the classmates I had in college who were paying to get a CS degree, I'd be surprised if many junior devs already working a paid job put much effort into learning rather than producing.
I wouldn't dismiss the implicit/subconscious aspect of learning by example that occurs when you are "just" producing.
That still comes back to motivation in my opinion. Using an LLM to generate code and using it without studying the code and understanding it will teach you very little.
I'd still expect most junior Deva that use an LLM to get their job done won't be motivated to study the generated code enough to really learn it.
A student is also only as good as the teacher, though that's a whole other can of works with LLMs.