I think it's housing, but then again I think everything in the post-globalization west is housing.
I got a graduate degree in Edinburgh, and the one thing I kept noticing about the entire country is how difficult and expensive it is to acquire housing. People literally ooh'd and ahh'd when they learned that a friend had inherited a small home in Norwich, saying she was effectively set for life. It's like California's NIMBY-fuel housing apocalypse, but on steroids due to the greenbelts.
The problem with a housing crisis, is that it's zero-sum wealth consolidation slow-motion event that takes place over a multi-generational period. A country's personal disposable income would generally pumped back into the economy constructively by/via entrepreneurs, but in a rent-seeking housing environment, that disposable income is lost to consolidated entities, who generally pump the excess rents back into further housing consolidation, or in international markets.
The reason it sneaks up on you is that once the housing freeze happens, you slowly fill in the excess housing capacity exponentially, until almost overnight, rents skyrocket. Suddenly, the nation becomes dramatically poorer within a decade or so.
The only good news to this theory is that it's trivially fixable with massive housing construction plans, the bad news is that it will be politically unlikely for people to suddenly vote to allow "ugly" new construction in the most historic and important cities in the country.
Just imagine how much capital Londoners could put to work if they had housing taken care of. As of 2017 they have been spending 50% of their income on rent: https://www.bbc.com/news/business-42179119