London had working class communities in East London, for example, in the 60s, the sort of streets where everyone knew each other and kids played together in the roads, which since then have been taken over by high earning young professionals and so the roads most definitely have a different vibe. Camden similarly completely changed. But at the same time, London is incredibly multicultural now, a lot of cultures from around the world, east to west, working and living there, lots of vibes intermingling, which has a lot of charm in itself. Camden now - the Georgian terraces, you will find social housing tenants, posh lawyers, artists and musicians, all living next to each other in respectful harmony - that was the case in my old street anyway - it was lovely.
I know what you mean though, too. I don't live in the UK anymore, and we have an amazing city near us which has changed beyond recognition by people from the capital moving there since covid - any opera or concert or ballet or performance is now booked up within hours (used to be available up to last minute), the atmosphere at play areas has changed, everything feels more competitive, prices pushed up, scaffold everywhere - if it affects someone personally and it has happened quickly it is natural that they will be hacked off by it, so I understand what you mean.
Lots of the Londoners moving to where you are now will almost certainly not originally be from London incidentally - if you get to know them, you will probably find their parents are from all over the country and they moved to London with jobs after uni. Some may even be secret muso's!