If you already used C++20 you aren't meaningfully behind, very little of interest has been introduced since then, and much of it isn't usable yet because of implementation issues.
I’ve touched on some of c++20, but haven’t used it extensively.
Specifically here are areas I haven’t used that appear to have nontrivial amounts of complexity, footguns, syntax and other things to be aware of:
* Ranges
* Modules
* Concepts
* Coroutines
Each of these is a large enough topic that it will involve time and effort to reach an equivalent level of competence and understanding that I have with other areas of c++.
I don’t mind investing time learning new things but with commentary around the web (and even this thread) calling the implementation and syntax a hot mess, at some point it’s a better investment to put that learning in to a language without all the same baggage.
I really wish c++ had gone with breaking change epochs for c++20.
