A few examples:

• CTAD: Instead of std::pair<int, int> myPair{ 1, 2 }, you just write std::pair myPair{ 1, 2 }
• std::optional, std::variant and std::any
• Guaranteed copy elision in some cases, making it more feasible to apply the rule of 5 everywhere
• Attributes like [[nodiscard]] (compiler warning if an object or return value is discarded) and [[fallthrough]] (suppress a switch fallthrough warning)
• Generic lambdas ([](auto it){ /* do something */ })
• std::string_view, which is much safer as a function parameter than const char*

Even C++11 is pretty old. I would recommend at least C++17

Like all of the footguns in C++, it’s only a problem if the codebase uses it wrong. When used correctly (i.e. only when behaviours mimic built-in types, and without side effects), it helps makes code more readable

Don’t do what numpy does, which is to define * for two arrays. Without learning the library, you wouldn’t know whether this performs element-wise multiplication, matrix multiplication, dot product or cross product. Worse yet, it behaves differently to Python’s built-in * for lists (which is also bad), which concatenates N copies of the list

and has at least three contributors, give or take

You can’t make a minimum approximate. Does two contributors count? Just for some, but not others? This just gives them more leeway to include bias in the decision to ban someone