>It used to be that they would have been forced to seek help from a senior engineer

You still have standups, right?

I'd be questioning why at the very least the team lead/manager isn't questioning the lack of progress during those meetings and immediately requesting a more senior engineer help out.

Even before AI this was how it worked. Unless the junior engineer is being purposely secretive about lack of progress, which would have happened back then too, then this isn't an AI problem, it's a team culture one.