From Neil O'Brien's substack piece on graduate visas linked above
"Regular readers will know that since the launch of the graduate visa, student visas have massively increased. It has not affected numbers from developed countries, but has been one cause of a huge expansion in numbers coming from developing countries.
"This is likely because of the opportunity to work in the UK with no minimum salary requirements is much more valuable to people from poorer countries (this is not a criticism of them, just a description of the incentives here)."
I was expecting to see that student visas were partially driven by graduate opportunities, but that jump is even bigger than I was expecting!
(edit as image is under review: screenshot of the graph of student visas in the section "The story so far". The graph shows that student visas rise dramatically when there is a post-study work visa available and fall when it's withdrawn. Since the new graduate visa came in around 2020, student visas from India rose 10x (200k vs 20k) and also rose a lot from Africa and the rest of south Asia, but stayed constant for countries like the US)