Maybe it's a way to kick people off the old models. "If you still want to keep using the old model you can, but you'd better pay a premium."

I work for Google and their free, internal Gemini API isn't quite as graceful. They once turned down a model arbitrarily and it broke our tests. I had to scramble to fix it, then build warning systems for the turndown as well as a special validator to make sure any upgrades make the same determinations.