This is nothing new, Azure has been having capacity problem for over a year now[1]. Germany is not the only region affected at all, it's the case for a number of instance types in some of their larger US regions as well. In the meantime you can still commit to reserved instances, there is just not a guarantee of getting those instances when you need them.
The biggest advice I can give is 1. keep trying and grabbing capacity continuously, then run with more than what you need. 2. Explore migrating to another Azure region that runs less constrained. You mention a new region would be complicated, but it is likely much easier than another cloud.
On AWS instances are only reserved if you reserve a specific instance type in a specific zone. Reservations across multiple zones or savings plans don't reserve capacity.
In the AWS context, they are, in fact. That's the original point of them - so during big AZ failures your reserved instances had first dibs on the available capacity.
The billing thing became more of the point as big AZ failures are so rare.
The biggest advice I can give is 1. keep trying and grabbing capacity continuously, then run with more than what you need. 2. Explore migrating to another Azure region that runs less constrained. You mention a new region would be complicated, but it is likely much easier than another cloud.
1. https://www.zdnet.com/article/azures-capacity-limitations-ar...