Best advice - not to use C wherever possible. There are better languages for many areas. Speaking from my decade of experience as C programmer.
This is probably because Ada was mandated for government projects. The people buying compilers were most likely able to charge that expense to the government, possibly even with a mark-up.
The language had a weird temporary resurgence a few years back. It seems to have started by the free Ada compilers becoming decent and by people starting to get serious about security holes. It seems to have ended due to rust claiming that niche.
In production code powering high integrity systems, certified compilers and industry safety norms, Rust still has a lot to catchup over Ada.