You right, because the main companies with OSes that contribute to the surviving compilers that still care about ISO, are now focused elsewhere.

Apple with Swift, Google with Go, Java/Kotlin, Rust, Microsoft with C#, Go, Java and Rust.

Most modules stuff on GCC was done by a single developer, if I am not mistaken.

Notice how Visual C++ blog posts are mostly about game development related improvements, Visual Studio tooling.

Everyone else their compilers are still stuck on C++14, or C++17 if lucky.