There is a few problems combining to cause this issue. The first is that in order to get Wind farms to be made capital owners are requiring a minimum price for a MWH to ensure their costs will be covered. That isn't unreasonable given government wants them built but one of the reasons is because the grid isn't actually available yet with sufficient capacity to take their power but government still wants the farm built. So a compensation deal is agreed.
The various grid companies across the country are ridiculously slow in building out infrastructure, their backlog for projects goes into 2045 and they haven't expanded their capacity to compensate so even though the Wind farms are getting built and connected its often with lines not sufficient to take all their power at peak. The issue goes further than that because there are multiple companies and there is a lot of issues cross connecting the country. Scotland has lots of wind farms but no where near enough connection to England to pass the power down, so for large periods of time there is just excess wind in Scotland that no one can use and its the border between different grid companies so hence no ones fault. This backlog is also causing big issues with companies that want to install Solar too, they require permission from the grid and they aren't getting it.
Since pricing is done across the country as a single price what often happens is sufficient power is available but it turns out it can't actually be transferred so they end up bringing the gas turbines online, the algorithm doesn't take account of the limitations of grid transfer. If it did then batteries would make a lot of sense and could be used to reduce some of the problem and store the power excess but the incentives for that are all misaligned at the moment and again battery requires the national grid companies to connect them and a lot of battery projects are stuck in that backlog.
So the end result is paying for wind turbines to curtail while also paying for gas turbines, because the power can't be transferred from where its made to where its used and like all the private companies in the UK they are all about maximising profits and don't care if it brings the country to its knees doing it.