The traditional Conservative voter is a home-owner. So you might be a rabid socialist in your youth, but once you get a job, save up for a deposit, and buy your own home, you eventually transition to become yet another middle-aged Tory voter.
That pipeline is now broken - young people are unable to save up for their own home or get a mortgage, unless they have generational wealth. House rises have risen sharply and wages have remained stagnant, and now we have inflation - for necessities like food and bills - eating into what little people had to begin with.
The solution of course is damn the torpedoes and embark on a massive house-building programme like in the post-war period, but a) the post-Thatcher Conservatives consider that against everything they believe in, and b) current home owners - their ageing voting base - are NIMBYs who don't want the wrong sort of people living near them and any reduction in demand that would reduce their value of their homes (and they're going to need to sell their homes soon, to pay for social and health care in an increasingly threadbare welfare state).
The British press of course likes to blame "woke millenials" or whatever to keep their geriatric readership happy but this is the real reason for the collapse in the Tory vote in the under 50s.