The title is misleading marketing: It gives the impression you need this nice new blog post instead of all the old out of date ones, and that it's all you'll need to know for the foreseeable future.
Apparently too many people still keep using C++ compilers to compile C code, not surprising when there are schools still using Turbo C++ for MS-DOS as teaching tool, as per one of Bjarne talks.
Back to C++20, C++ is no longer my main tool, but I still follow up on it and one of my hobbies is checking new standard features, hardly everything works at is supposed to be and I expect the usual three years for stabilization, so when C++23 will be around the corner, is when I expect all major compilers to fully support C++20 without triggering some kind of compiler error.
That's not surprising as modern C++ predates C++11. Newer standards "merely" make it more convenient to practice it.
At the end of the day, modern c++ is really about emphasizing value types, RAII and parametric polymorphism as opposed to OOP.
Anyway, these days we have it good conformance to new standards comes relatively quickly. It took forever for most compilers to be C+98 conformant (and technically most never reached it).
An article using C++20 will just lead to frustration, as there are still rough edges using concepts, with a standard that was just published last week.