Am I wrong?

So my boyfriend (17) and i have been together for well over a year and because of covid we are facetiming to stay connected (my mom is high risk) but for whatever reason his brother (18) keeps telling on him for being on the phone at certain times, like late at night or if we haven’t talked because of summer class and whatnot he will talk to me while he takes a shower before he has work to do. His mom more often than not takes his brothers side and my 17 year old boyfriend gets a bedtime because his adult brother tattled. I really try not to get involved because i don’t want to stir the pot but i’m really coming to the end of my patience when it feels like i’m dating a toddler. I don’t understand why his brother feels the need to tell his mom about when we talk considering it’s not a big deal. The late night talks have come to an end mostly because they do share a room and i understand, but what we do in our time when it doesn’t concern him shouldn’t be his problem. Because we are all the same age (him and all his siblings and me) i don’t want to start something. Am i wrong for getting annoyed? I am also annoyed that my bf does nothing to combat this because he doesn’t like conflict, and he lets his brother get his way about most things.

thank you if you read this far!