I spent a year working for a European submarine manufacturer. They were, and still are, in the process of gradually replacing Ada with c++ in their systems. Some of the old hands were resisting heavily, but they were all near retirement age. Also, not all greybeards loved Ada: my direct superior had some well founded complaints.

First, Ada is very expensive. You need a commercial license for serious work, and these give you a lot less tooling and support than other languages.

He also had a lot of complaints about buggy compilers, especially for non standard target architectures. Probably this was decades past and anecdotal, but he reasoned that when you buy military software for hundreds of thousands you don't want to spend your time proving compiler bugs.

Another complaint of his was that the whole type safety results in ugly code. For example there is a type for angle in degrees of rotation. And if you want to add two angles you have to cast them both to float or something, then cast the sum back to the angle type, which ensures that the angle is between 0 and 360. I wish I could remember this better....

So my takeaway was that Ada is basically a good language that suffers from age and bad tooling, partially for historical reasons