Tracfone AT&T sims went from QCI 8 to 9 as well a couple years ago.
I'm pretty neutral towards AT&T's turbo feature here, the only bad taste left was for those who had unadvertised QCI 7 a couple months ago moved down to 8.
In my eyes it would have been a lot better for AT&T to include turbo in those Premium/Elite plans for free to keep them at QCI 7, while also introducing this turbo add on option for any other plans or devices. As it stands now only a handful of plans can add it, and only if you're using a device on a random list of devices AT&T considers to be 5G smartphones.