I totally agree that OPP (and C++) are more often than not atrociously taught, I've said that here in the fora quite often.
The problem devolves to a lot of those making and setting the curricula are not people with a lot of experience in coding C++. They might be (barely) adequate C coders, of a C that is years and decades out of date. And a lot of the instructors fall into the same category as well. Or some other language like Java and they think C++ and Java are equivalent. PFFFFFFFFFFFFFFFFFFFFFFFFFT!
A lot of the material available for self-teaching, books and online videos, especially the videos, are just plain bad. My programming library is chock-a-block full of not-good tomes.
Another consideration is even recently published books are notoriously outdated by the time they see print.
One book I've found that teaches C++20 quite well, published in 2020, up front mentions there are parts of the C++20 stdlib that at the time of publication not one compiler was able to compile the code.
Another book published earlier has a cover blurb that it covers C++14 & C++17. Well, other than a couple of paragraphs about what C++14/C++17 added to the toolbox with NO example code the book reads as if it were written to target C++11 only.
I've glanced at a later edition of the same book that blurbs it covers C++20. No, it doesn't.
Having up-to-date compilers is also a "must." Visual Studio 6 was horrible in allowing things that violated even the C++ standard at the time.
Learn C++,
https://www.learncpp.com/, is one of the better online resources for C++, and it is free. Not comprehensive, but it does teach the basics and does it well.
12+ "chapters" before the site gets into the nitty-gritty details of OOP, though from the start it shows examples of using objects (objects are part of OOP, duh) from the C++ stdlib.
Formal classroom instruction setups could learn from the approach there. C++ is a huge "critter", trying to teach it all at once is folly. Learning C++ isn't a single semester situation.
C++11 transformed the language a lot. C++20 is almost as radical a change as well.
Going backwards to the 1980's is a stupid idea, and a disservice to students who need to learn how to code for the 21st Century.