I remember as a kid being existentially horrified at puberty. I mean, sure, I was trans without knowing it, but the idea of my mind changing to develop romantic and sexual attraction without my consent was terrifying. Looking back at the things I wrote as a teenager or twenty-something, I really was a different person.

We are always changing, forgetting, learning, being led by hormones and sensations, growing and decaying. Ultimately I don't care as much about whether who I am 5 years from now is "me" in some existentially meaningful way as much as I care about her being happy and having lots of happy people around her. I will live on in her memory.

Though if you're talking about your mom specifically rather than the existential horror of change, then yeah, mood. My mom sucks too, but she has never embraced change, and I've already learned to do better than her in so many areas. You can learn what she refused to learn, avoid the mistakes she refused to avoid. It takes work, but it's worth it.