For me, it's not about how the individual developer sees themself, but how the rest of the organization perceives that developer's skills. It's not unusual for a more junior member of the team to have stronger technical skills than someone in a senior role, just without the accumulated wisdom that comes with experience. But when stakeholders are fighting over scarce development resources, nobody wants a "junior" member of the team working on their very important task.
I'm not a fan of "Early Career Developer" as a title either. I prefer simply "developer", as it implies this person is a fully functioning adult capable of doing the work they were hired for. They may need more of my time up-front to line up tasks for them, but that's part of what separates them from "senior" developers.