I cannot remember the last time I saw C99 used. C codebases generally use C11 or C17, and C++ code bases use C++20
Also 8 and 16 bit embedded toolchains are certainly not on C11 / C17, they can hardly afford full C89.
That's the nice thing with C: it's much easier for small teams to fully support than the latest C++ standards.
That's A LOT of devices out there. A lot of which still get maintenance and even get feature updates (I'm working on one right now, C99).
So the claim that "C codebases generally use C11 or C17, and C++ code bases use C++20" intuitively sounds like totally untrue to someone working in embedded C/C++. I've been doing this for 15+ years and I've never touched anything higher than C99 or C++17.
If you're talking about gaming, sure. But that's not "C code bases generally".
Unless you think that code-bases created in the past year are a significant part of code bases that have been created since the inception of humanity.