We knew the writing was on the wall for Google Assistant when Google announced Gemini as its replacement. Things became more official recently when Google began killing off Assistant on phones in favor of the newer experience. But it appears that all hope isn’t lost, with one user finding a novel way to force a switch back to Assistant.
In a Reddit post explaining the process, the user claims they uninstalled Google app updates from its App info page, then opened the Assistant app on the Play Store (via Android Police). And sure enough, it works as expected, at least on my Pixel, and seems confirmed by a few others in the comments.