20 days are minimum. 24 only applies when you're working 6 days/week.
Generally, I'd expect 30 days. That's still the norm.
24 screams "startup" or "we struggled to offer that salary, so we're compensating with less holiday".
Re:Ask HN: Should I move to Berlin?
by adrianveidt on Thursday November 09, 2017 @10:08AM
(#15662995)
ebay gives ~ 24 days
> - 24 holidays per year
This is the minimum you have to get for full-time employment in Germany. In many companies you can negotiate more. (worth noting for the future)
I don't know much about Dubai, but from what I understand you'd also have much more to do in Germany. Easier travel to interesting places as well, since you can't throw a rock around there without hitting something historic.