A bunch of things but...
When Liz Truss became prime minister Labour was ahead by 2%in the polls, ie just a bit.
In her 43 days she brought in a budget with £45 million tax cut for rich people without actually showing how it would be funded. The IMF instantly said it was dangerous. The market reacted by plummeting the value of UK government debt (known as Gilts). These are "safe" investments used by many UK pensions to ensure they have solid liquidity. But the falling value caused them to start selling. This meant the value went down more. Essentially the Bank of England jumped in to prop it up by injecting £60 million. The pound slumped to its lowest ever value.
In hours she broke the UK economy. We the tax payers lost £30million we never got back. When she quit Labour had a 25% lead that has hardly changed to now.
That's really where they lost it.
Yes Brexit has made us all poorer, yes we've now got very high immigration as we're not training our children and we're an aging population. They have raised taxes but cut services etc etc. It's been essentially a bad 14 years. Life expectancy is down over 3 million use food banks to eat etc.
We need to except we're a poor unimportant country now and need to reshape our expectations as a result.
