Actually, I think it is the "genAI" as part of writing tools and Siri update. I think I misremembered for my description and it was being applied to form fields for different configuration panels.

I just tested it with text inputs on a form. It triggers with peoples's names from your contacts. It also triggers with capitalisation like typing something like "fedex". If you type really quickly you're fine, and if you type slow you have time to play with the settings. Speeds the middle with these "Spelling and prediction" settings end up with text changing. Enter and space seem to always trigger. A delay thinking of the next word seems to sometimes trigger. Seems new to me and the contacts suggestions seem aligned with the integrated Siri they're advertising (and sure technically you could probably say it isn't genAI)

Anyway, I'm turning the settings back off now