Opinions on parenting/stepchild

So me and my partner have been together a yr and we live together and he has a kid and has full custody(mom is not really in the picture seen whenever really but not super consistent) well anyways when his child sees mom they come back like full of hate and is rude and disrespectful and he had to come home from work early bc of it to “punish “ child but instead it felt like a whole lot of rewarding instead and I found a note and it says “remember who was there for you when you didn’t have no one” like something along those line and had his kids name and was like show “child name “ I’m still daddy I love them and I know that for sure. “Like what’s that even mean? I take care of your child 24/7 and our house and I also work 2 jobs???