https://www.telegraph.co.uk/news/2022/10/30/glastonbury-festival-may-forced-lower-capacity-combat-illegal/
It's behind a paywall so I can't read it all, but I assuming this is BS.
This seems to be referring to the council discussion over front of house drugs testing (reported a few days ago).
The police nor council do not have access to the number of drugs seized by security, so someone simply commented that an increase in security or a reduction in numbers attending the festival would affect the figures for the number of seizures.
That appears to be where this story has come from. I've not read anywhere that anybody at the meeting actually called for a reduction of capacity. Not sure how soon MDC publishes the minutes of their meetings and can't see it online yet, but if anyone has access to the full article pease post it up.