It would seem the Home Office has now acquired the ability to impose, without visibility or accountability, shadow bans on students coming to British universities from particular countries. How? Because of the interaction between indiv visa decisions (made by HO alone) and visa rules for unis 1/?
Anecdotally what seems to be happening is that the Home Office is refusing all student visa applications from certain countries. The Treasury should have told them to knock if off years ago but at this point the FCO needs to tell them to stop trying to cause an international incident.