I suspect it’s dual-band acceleration (sometimes called “speed boost”) - you’re using both the 2.4GHz and the 5GHz bands. WiFi 6 and 7 will probably show a 6 and 7 respectively, and voice over WiFi is shown separately as you say.
Try finding it in your settings, turning it off, and seeing if the + disappears?
I suspect it’s dual-band acceleration (sometimes called “speed boost”) - you’re using both the 2.4GHz and the 5GHz bands. WiFi 6 and 7 will probably show a 6 and 7 respectively, and voice over WiFi is shown separately as you say.
Try finding it in your settings, turning it off, and seeing if the + disappears?
Seems like that could be the reason. Network acceleration was on.