Yes, after we create AGI it will stagnate at human like level of cognition because AGI with more advanced levels of cognition can't find product market fit.

(serious) I don't get the reference, do you mean a stall in AI progress or a brief overall industry-wide disinterest in it?

The term AI winter usually refers to the late-80s collapse in AI funding after the technology of the time (particularly expert systems and Japan's "fifth generation computer" project) failed spectacularly to live up to the hype.

Before that, there were other downturns in AI funding after early technology turned out not to pan out so well. For example, the late 60s' effort at machine translation.