I think the biggest drag is actually rent prices. When I got to Berlin 20 years ago you could get a room in a shared flat for €100. That same room now would be €500. Same for music spaces: it was easy to rent unused warehouse space in the inner city 20 year ago. There are a lot of interesting things that happen to a city when rent is ridiculously low as it was in Berlin for a long time (there were more apartments than people).
There's still a lot going on in Berlin, but the character has very much changed. 20 years ago it was rare for clubs to be legal. Most of Berlin's well known clubs now started off as illegal clubs back then. But there were hundreds of other spaces that didn't survive and transition to being legal spaces. There's still some of that, but much, much less. Also back then just randomly setting up a sound system in a park in the summer was much more tolerated. "Open Airs" in Berlin were just kind of what you did in the summer.
Honestly, while I generally did not partake in such, the pandemic was the first time that I realized that came back some. Partying was illegal and the parties were moderately guarded secrets. I hadn't seen that much buzz around illegal parties in more than a decade.
Addendum: As a weird note, I don't even get the grandparent's comment about Potsdam? For the non-Berlin folks, it's a city just outside of Berlin's borders, but an hour away on the train from the more alternative bits of the city. It's neither known for its music scene, nor honestly as a place that rich people want to move. I know a couple of people that have moved there because of usual suburb reasons: they wanted a bigger place, and it's cheaper there. The other cities listed there are also weird. I've been out in all of them but Lyon and, yeah, there's some stuff, but to say the "scene" is moving there is really off. Three of the cities listed there are in the Balkans, but the best city for techno in the Balkans is undoubtedly Belgrade.