There were two step changes: ChatGPT/GPT-3.5, and GPT-4. Everything after feels incremental. But that's perhaps understandable. GPT-4 established just how many tasks could be done by such models:
approximately anything that involves or could be adjusted to involve text. That was the categorical milestone that GPT-4 crossed. Everything else since then is about slowly increasing model capabilities, which translated to which tasks could then be done
in practice, reliably, to acceptable standards. Gradual improvement is all that's left now.
Basically how progress of everything ever looks like.
The next huge jump will have to again make a qualitative change, such as enabling AI to handle a new class of tasks - tasks that fundamentally cannot be represented in text form in a sensible fashion.