As someone who occasionally watches competitive programming for fun (and competitive programming is basically competitive whiteboard interviewing) it gives me quite a bit of perverse pleasure that even in languages with great first-class class and object support the norm is to write functions that operate on global variables.
Where do you go to watch competitive programming? That sounds like it might help with Leetcode-style bullshit.
I just follow a couple YouTubers who make videos about it. For example: