Mostly non-technical things: continuity (or, rather, the lack thereof) and PR.

Continuity: Ada is not widely taught at universities, and, whilst the AdaCore’s GNAT Academic Program (GAP) does exist, one has to consciously seek out a university that offers a course in/on Ada. Ada and programming in Ada is not common knowledge, which stems from the next point.

PR. Ada, rightfully or wrongully, does not exactly bask in the limelight of popularity – most assuredly not to the same extent as Python, NodeJs, Typescript, C#/.NET etc do. The current generation of Ada developers do not care (and probably should not), and the young and future generations of potential Ada developers miss out. Ada is not talked about in diverse contexts spanning web development, frontend/backend[0] development, containers, cloud – and the list goes on. Not because Ada can't be used in any of the aforementioned contexts, it is just that due to the lack of PR it remains an unnoticed reality – kind of like «if a tree falls in a forest and no one is around to hear it, does it make a sound?»

[0] Yes, «frontend development» and «backend development» are the fancy terms in wide use that the new generation can easily understand.