It could be an exponential graph, but it could also be a discrete step chart. When you're at the point where a leap in technology is happening, it looks like it's exponential for a brief period of time. But after that jump, things remain largely flat for indefinite periods of time. This is what leads to AI hype cycles and AI winters.
Another aspect to consider is that a lot of the recent growth in AI is economic, not technological. The kind of language model that makes Hacker News headlines today is a thousand times larger than models were four years ago. GPUs haven't gotten a thousand times better, and the underlying algorithms aren't a thousand times better; companies are just spending a lot more money. There is no particular reason to expect that trend to continue indefinitely.
