I figured I'd add my two cents since I'm still a juniorish developer (sitting at around 2.5 years of experience) and I definitely noticed during my my more recent job search that there was a dearth of Junior job postings. I'm of the opinion that there are two major issues in play:

1. There's the myth of the junior developer breaking prod or wiping databases. This is usually the result of teams not having enough process or protections in play. These are only exposed when a newbie developer does something silly because senior developers have learned how to navigate the system.

2. There's the myth of the junior developer not adding value until they're fully trained. Personally I have never had an issue ramping up, but from what I've seen across my network and search is that there's a fear of developers leaving once they gain enough knowledge. And, well, that usually happens because junior developers can be heavily underpaid without any promotion opportunities which makes job hopping the best way to increase your salary.

So I would say right now there's an overabundance of mid-level positions that could be filled by junior developers but due to irrational fears results in them just foisting the work upon smaller teams. I definitely noticed that the moment I hit two years of experience that the search became a lot easier