Is it normal for a mom to gossip about her adult children?

My baby shower was a few days ago and one of the activities we did was to pass out little note cards so people could write a message to my baby, for him to read when he turns 18. One of my mom’s friends was there and her message talked about how a few days before I announced my pregnancy to my mom, which was a few weeks before my wedding, my mom was complaining to this friend about how much of a b*tch I was being. It’s funny because my mom was the biggest source of stress for me during that time, she would often call me screaming and crying asking why I was planning that wedding the way I was (it was a micro wedding and she wanted me to have a big wedding), telling me it was so weird to get engaged/married in less than a year, and more, and when I went low-contact with her she had many meltdowns asking why I hated her, telling me she wishes she left our family when I was a baby instead of my dad who left us, etc. So in this card to my future son, her friend told my mom ‘maybe she’s pregnant’ and that’s why she included this in the message.

My mom often tries to gossip about my own sister to me, calling her a b*tch to me and telling me her husband (my BIL) has no balls (he’s actually a good husband). I’ve learned to shut these conversations down bc they’re toxic and I love my sister. She has also badmouthed everyone in my family (grandma, dad, aunts/uncles) except for my brother. And now I know that she also gossips about me to whoever will listen. Is this normal for a mom to do? I get that everyone needs to vent sometimes but this seems excessive?

I’m mainly asking because I plan to NEVER let her be alone with my son, and if I hear her saying weird shit to him trying to undermine my parenting, I will cut contact even further. I’m not sure if I’m being too extreme.