I had the same experience. C++ doesn't even compile or I have to tell it all the time "use C++23 features". I tried to learn OpenGL with it. This worked out a bit, since I had to spot the errors :D
What kept me as an intern during education is the feedback and the nerdy chitchat. Developing as an intern in a team, where you have your own project and the possibility to chat with experienced people from various fields can be a huge impact. I had no deadlines, so if someone proposed a better way to do something I tried it and I learnt a lot from that.
Besides, talking to other people face to face about your project always gave me a huge motivation boost.