Interesting to note that population of central boroughs of London (which is used as a canonical example of population growth and overcrowding in Europe) is roughly half what they were 100 years ago. e.g. https://en.wikipedia.org/wiki/London_Borough_of_Islington#De...

And likely decreasing now again, as people find less cultural benefit of living in an expensive city during an ongoing pandemic.

I don't think population size or density is really the problem - the problem is poor planning to account for probable changes in population size or density. Consistent 2% growth should be relatively easy for politicians to anticipate and manage.