Is there a safe subset of C++ defined somewhere? Can I turn off some of these ridiculous "features"? As we add so much to the language, the number of footguns increases quadratically.
You do not have to use these features if you do not want to.
C++ is very powerful, and has an amazing world of libraries available, but sometimes I feel like it is at least two languages at the same time.
For example, one benefit of using C++ over C is writing C style programs with modern libraries and convenient containers in the STL, but you quickly learn that C style programming isn't supported across the board, and hitting that wall can be jarring and unexpected (Looking at you openCV - just try to allocate space for a struct containing a cv::Mat)
https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines
I sympathize that compilers do not do "enough" of this for us. But there's really no substitute for a good code standard and developer culture focused on quality.
https://isocpp.org/files/papers/CppDevSurvey-2021-04-summary...
If you check other well known survey among C++ community you will see similar results in static analysis tooling and coding standards adoption.
So while, contrary to the C community, WG 21 members do strive to push the code quality forward and publish tooling that helps to enforce it, the adoption could be much higher than it actually is on the field.