Smart juniors shouldn't be juniors long. I think another angle to think about this is Junior devs that can leverage AI to learn have a much shorter path to Senior than current Seniors had to take (aka the hard way). If as a Junior you know of things to look out for but don't know the implementation details, AI can help you.
For really obscure issues or bugs, I had to scroll through seemingly random StackOverflow results (or Experts Exchange, ha) looking for exact issues that I had, weeding through answers that weren't relevant, things based on older versions, etc. Now you give the context to AI tech stack, data, and your source code, explain the problem with the error message, and ask what might be happening and that shaves a few hours off the old way of trial and error. Even if the 1st answer isn't totally right, a few follow on questions will help narrow it down.
The tradeoff is that searching for answers develops people's ability to do research in general. It's an essential skill to be able to skim though material quickly and decide if it's relevant or not. it's in the same way that calculators save labor on large calculations, but giving up all of one's mathematical intuition in exchange for a better calculator would be decrease in net performance.
For really obscure issues or bugs, I had to scroll through seemingly random StackOverflow results (or Experts Exchange, ha) looking for exact issues that I had, weeding through answers that weren't relevant, things based on older versions, etc. Now you give the context to AI tech stack, data, and your source code, explain the problem with the error message, and ask what might be happening and that shaves a few hours off the old way of trial and error. Even if the 1st answer isn't totally right, a few follow on questions will help narrow it down.