Way reduced offer grades than typical offer (BBC v ABB)

I recently got a conditional offer from Reading to Study Computer Science, and the offer grades were BBC. The typical offer is ABB, does anyone know why out of interest?

There was talk around my sixth form about some people getting reduced offers because our school is underfunded. Not sure if this is accurate however.

Thanks

Their contextual offer is two grades lower so this looks pretty normal:

https://www.reading.ac.uk/ready-to-study/study/what-offer-will-i-get