Idk where your from but where I am, the natural progression of friendships is yk at first games, then discord. Then, when your like friends, close but not rlly close, your friends on instagram since its not really that personal, at least for me. So you dont risk private info apart from your face. And then after that is you become friends on fb. This is only true for friends ive met who is also from my country though. But usually its always discord-> insta
Different countries use different apps. I dont remember what it was called, but their was an app that (i think either Chinese or Japanese) that used an id or phone number (kinda of like WhatsApp) (i just no i could never actually create an account, it was annoying) that they primarily used. Russia, discord is banned. So they dont use discord. Ive played a variety of games with people from all over and a ton of different forms of communication. Apps like WhatsApp that use phone numbers were pretty common. It also depends on the age group of said people too. Ive noticed a lot of older people leaned towards WhatsApp more then discord
contrarily it’s very normal depending on the person and situation! the two of them are 1. solidly friends at this point, at least in jihan’s eyes. and 2. also grown adults who can make their own decisions so it’s really not a big deal lol i’ve personally shared my number with plenty of online friends i trust over the years! having text / message access is just more convenient than message apps if you want to keep talking to the person depending on the circumstances and situation. they DO use Discord too but it’s solidly for in-game chat, particularly VC.
yoochae has his reasons for denying him that aren’t related to not wanting to anyway! but it’s really not that big a deal that jihan wanted to trade numbers

If you're playing together long and close enough ESPECIALLY in same country, it's actually makes sense. Moreover, both of them are men so usually they are not really cautious and doesn't have to think about sexual harrassment or anything like that.