I can’t say anything on other places but for Britain it’s political decision making. It would be easy to say Tory Austerity (which is a massive part of it) but the root cause goes to the Thatcher neoliberal agenda.
Selling off massive parts of Britain without reinvestment in industry, allowing large areas of the North to descend into poverty, which has seen massive social issues created, creating ongoing issues for local government.
Removing any control on financial institutions, which allowed them to turbo charge credit. This for a time created the illusion that growth had been achieved, but ultimately it resulted in massive increases in land and property value, which further increased inequality. Cheaper credit allowed normal people to think they were wealthy, but uncontrolled credit resulted in the 2008 financial crises, which very nearly caused the economy to implode.
2008 meant the British government acting like it had to during COVID and creating billions to stop banks going bust. It was the only choice available, but banks withdrew almost entirely from lending. Suddenly, small businesses weren’t supported, bigger business forced into austerity measures by banks desperate for their money back and the knock on effect was recession. Lots of employees were give a choice - take a pay cut or lose your job. Some took a pay cut and still lost their job.
The 2010 election allowed the Tories to create the lie it was Labour’s fault (how that was allowed to stick is incredible). Once Tory Austerity kicked in things really got worse.
Just looking at the state of roads all over England is the symbol of austerity. Local government was massively underfunded causing them to cut back on everything. Proactively maintaining roads was now impossible. Roads are only fixed once they become dangerous.
With local services cut to the bone and all national government services reduced, society started to feel very different. This ultimately led to Brexit, which was always going to be a total disaster.
In light of all that, just blame poor dark skinned people on all your problems. It’s clearly their fault trying to make a better life for themselves in a country many have connections with.