Haha! No I’m afraid nobody will have an old planet file from 20 years go, since the OpenStreetMap project only started in 2004!
Also looking back to early planet files (from 2007) will not really give you much interesting historical data about the way world was back then (maybe some, but not much) because you’ll mostly see the limited map coverage that the OpenStreetMap project had back then. There’s a big difference between looking at the history of how OpenStreetMap data has progressed, and looking at the history of how the world has changed.
Since you are interested in the history of how the world has changed (how Freiburg was 20 years ago)… your best bet is to get involved in ideas and initiatives around Historical OSM. There’s a mailing list you can join etc. But there isn’t really much software geared up for answering these kinds of questions, and certainly not much data at the moment I’m afraid.