In the end we had about the same disposable income.
Also: It’s free money?
You are legally entitled to childcare for kids 1-3 and can sue for loss of income.
Also consider a “Tagesmutter”, finding the right one can be difficult but for high income people it’s usually not too much of a problem.
If you have lots of space an au-pair might be sensible, the costs can again be tax reduced to some extend.
tech workers rarely are "middle class". not even "upper middle class".
We tend to have a contorted idea of real income percentiles.
The average/median person was always dirt-poor and struggling to survive. Of course in the developed countries that has changed quite a bit in the last 60+ years. Still, since it feels like we are slowly reverting to the pre WW2 status quo, I'm not sure we shouldn't entirely base it on population percentiles (instead of using some more "arbitrary" wealth/income cut-off that's adjusted by inequality)
Your idea of decent might be a bit off...
That's not to say that buying in Germany is absurdly difficult and expensive. It absolutely is. But if you think 4k net doesn't make you well off in average Germany you're really extremely bubbled.
You won't be buying in downtown Munich, but that's very far from average Germany, and you could definitely be buying within half an hour of decent public transport to downtown munich.
The mortgage is estimated at 1600€ / month, S-Bahn to Hauptbahnhof is 22 minutes.
It's not super comfortable (as you'll be paying bills on top) but absolutely doable on a single 4k€ net income.
It took me about 2 minutes to find this.
Edit: To note, I claimed it's easily doable in the Berlin area, not in the Munich area. In the outskirts of Berlin 4k Net is more comfortably doable. Berlin is also geographically larger, so travel times will start being significantly above 30 minutes, too, though.