I am a current operator of multi-family housing in Gangnam-gu.

I am currently renting out a 25-year-old multi-family house (to be precise, I manage the one my parents own).
There isn't much difference between the deposits and monthly rents 25 years ago compared to now.
In my experience, they seem to have risen by about 20–30%.
Back then, there were quite a few newlyweds or young couples,
but now, I see many single occupants, especially elderly people living alone.
The point is, while apartment prices have skyrocketed, housing for the working class hasn't risen that much.
What is in short supply are apartments, not studios or villas.
There is an absolute shortage of apartments in Seoul.