Developers (often juniors) use LLM code without taking time to verify it. This leads to bugs and they can't fix it because they don't understand the code. Some senior developers also trust the tool to generate a function, and don't take the time to review it and catch the edge cases that the tool missed.
They rely on ChatGPT to answer their questions instead of taking time to read the documentation or a simple web search to see discussions on stack overflow or blogs about the subject. This may give results in the short term, but they don't actually learn to solve problems themselves. I am afraid that this will have huge negative effects on their career if the tools improve significantly.
Learning how to solve problems is an important skill. They also lose access to the deeper knowledge that enable you to see connections, complexities and flows that the current generation of tools are unable to do. By reading the documentation, blogs or discussions you are often exposed to a wider view of the subject than the laser focused answer of ChatGPT
There will be less room for "vibe coders" in the future, as these tools increasingly solve the simple things without requiring as much management. Until we reach AGI (I doubt it will happen within the next 10 years) the tools will require experienced developers to guide them for the more complex issues. Older experienced developers, and younger developers who have learned how to solve problems and have deep knowledge, will be in demand.