Yes tethering is absolutely one of the parameters - including whether it’s enabled at all and whether it goes over its own separate APN (which is how the carrier can limit it or throttle it separately from the main data plan) or is sent in-band over the main APN used by the system (alongside other params like the number of client devices connected to the hotspot if I remember correctly). Android has a similar “carrier settings” database, although I haven’t looked too deep into what kind of settings are available.