I came multiple times across similar individuals as you have just described. They are very good at talking in details about a tech subject, charismatic, defensive and argumentative all day long over their solution even though it does have lots of holes. But when it comes to actually implementing a task. They usually fall short. They will quickly grap an existing/similar solution from ie github., spend many hours trying to understand it, Then copy-pasted and present it as their work (half-baked solution)

Even though the whole thing could be very simple. Another thing is, they will come up with reasons that the issues with the user story/task for code/solution is due to environment or some other reasons like tools, framework, scalability and "bs".