My local council has just voted to increase the salary of its "Chief Executive Officer" from £160,000 to £190,000. That's more than the prime minister's salary for a job which is really just the hired help, it doesn't come with responsibility and accountability in the way that a real CEO in industry would have, and the most recent one left recently (for more money at another council) without actually being put on paid leave of absence for months which happened to some of her predecessors. It's unfortunately become "baked in" to local authorities now to pay so much for this non-job, and it's just one example of the contempt with which they treat our money. Many councils are now in hock to a group of people who set their own salaries and flit between councils at our expense.Councils haven't been splashing their money around since the austerity drive ten years ago and counting.
Councils have been finding that the demand for, and cost of their statutory functions (particularly social care) has been increasing substantially. Fundamentally, this is what these problems generally boil down to.
To me, this is actually off-topic because it doesn't matter what hue of local council you have, they're all at it.
However I think Starmer needs a manifesto policy to "do something" about local authority finances, he can't please everyone and shouldn't try too hard to do so, but I think plenty of people from all sides of the political spectrum realise what a mess local authorities now are in, some of it their own making but a lot of it thanks to central government.