Generally, large C projects have their own style that is followed whether the code is new or not.

And thus it’s surprising to me they haven’t changed their style moving forward when it’s known that this is error prone.

Large stable projects are very much wary of wide-scale changes their codebase. What they have is tested working by decades in production. Especially with C where tooling is brittle.

Let me put this way: If you submit a code prettifying patch to the Linux kernel, it will not be accepted. The risks aren't worth it.

The only real way forward is full migration away from C, for which a better scope is a separate project.