I don't think this behavior has anything to do with AI although it seems like it's been used as an excuse to justify it. Everyone seems to be in a belt-tightening risk averse mode right now and that means cutting junior positions and leaning on smaller teams of senior staff. You can see this behavior in more than just tech and more than just positions that can be replaced by AI. The job boards betray it as well, job postings for junior staff have dried up.