ExGrunt
How would the service provider know when data is encrypted end to end by many phone systems?
This is a bit of an old wives tale from the days when unlimited data contracts were available but movie streaming was rare or impossible because the mobile data network wasn't fast enough. With 3/4G connections now widely available, the mobile companies would like to restrict the amount of data they have to shift. This is achieved by imposing daily download limits or by throttling internet connection speeds for those of us that still have unlimited data plans.
Nothing to worry about. If your phone or tablet is prevented from acting as a hotspot, that function is disabled via the sim card you have installed. If you can see you have hotspot capability in the setup screens, you can switch it on and use it.