This redesign for Assistant's settings appears to be rolling out widely to (almost) everyone. Many of our readers and Android Police colleagues have it now.
The old Assistant settings UI was just one long screen broken up into sections for account, devices, and services. The new settings page has tabs, and the organization is a little more rational. On the left, you have Personal Info. That's where you can change your nickname, payment info, and so on. Next, there's Assistant. This is where you change the settings for Assistant voices, languages, home control, and additional Assistant features. The Services tab has all of the settings for devices and services that are connected to Assistant.
You can see how the new settings screens look in the images above. Nothing strikes me as out of place aside from the home control menu. I think that should be in Services rather than Assistant. Keep an eye out for this UI to appear on your devices.