i reread the chapters and jaehyuk was pretty valid to be cautious with his mom. she was homophobic to them the first time they met, she told garam if she was going to contact him she would only have negative things to say and that she doesnt accept them or their relationship. that was even the first strain too for their huge fight
yes he isnt exactly polite with his mom. honestly it just looks like his mom is the strict parent and seeing how much of a menace he has always been they butt heads a lot. his mom is the same too, shes always harsh with him and always assumes hes done something wrong again so hes also always defensive, its just the dynamic they have

His mom isn’t even bad why does he react to her like that??
I’m gonna miss them so muuuchhhhh