AI because it’s not up to date with the evolution of the language.

😯
May I ask, what kind of niches that are?

Admittedly, I work in industrial automation, where tool changes happen rather on a scale of multiple years than months, but I find it hard to imagine projects in which the whole C++ development base changes in less than half year intervals (as that is a typical knowledge-cut-off period for frontline models).
But even than the models will know the working state of the C++ standard proposals, which typically don't change that much any more during the last few months before official release.

Have they considered supplying updated specs and guidelines via RAG? Or just preloading it into the context?