Advice on this sibling rivalry

So my older sister has a 3 year old girl that is behind her age when I try to give her advice that I was given or suggestions that she should try she shuts them down. She has always said that she isn't behind or advanced she has her "own category". I have a 9 month old baby boy and anytime he hits a sleep regression, he is going through teething or he's just angry she tells me he needs to go to the Dr. Just for added context he has been hitting all these milestones well before her child has and she's now lying about when her child hit these milestones. I don't know if she is trying to act like the perfect mother or what. Idk why but it bothers me so much. She is a TV parent 100% since her baby was born she would just sit her kid in front of the TV while she worked and her BD would play videogames all day. (Not shaming her for working) I'm lucky and get to be a SAHM but I feel like she wants to seem like I'm doing everything wrong and she does not agree on alot of my parenting choices as it is. Has anyone else went through this? What should I do??