Central government cuts to budgets, inflation, increased adult social care costs only able to raise council tax by a few percentage points as more wouldn’t pass a referendum?

It was basically government policy for them to be ‘enterprising’ to have any hopes of covering costs with them trying to get to the point of removing central govt subsidy wherever possible.

All it then takes is a couple of projects failing or a lawsuit (ala Birmingham) that lead to unexpected expenditure and they hit effective bankruptcy.