The size of the core funding cuts to councils by HMG outweigh everything else the councils are facing according to the figures.
Now, purely by memory, I recall commentary over the years that 1) David Cameron was cutting taxes on various categories of land assets to benefit large land asset holders to the detriment of the budget, 2) the battle of any tax cuts are spending programs in disguise vs no they aren't and 3) May, Johnson, Sunak, Starmer etc have not reversed any of the tax cuts put in place by Cameron.
There's no doubt a more delicate story to what has happened, but a fact check of this into Deepseek before I posted this confirmed that the throughline is credible.