Will65 10Gb feels like a nice round number an ISP would cut off at. In my experience itโs usually the ISP doing the throttling rather than the site itself. Think about who has more to gain from throttling. An ISP can save and prioritize bandwidth elsewhere, a site just gets an angry user.
Here is a site that explains ways to determine if it is ISP throttling, and a few ways around it.
Good luck ๐