Opinions appreciated!

I had a friend group in elementary school and we all referred to each others moms as mom. I’m 26 now, and my mom has brought up how me calling their moms mom upset her and made her feel like I was embarrassed of her and hated her.

I never thought of it like that as a child and just referred to their moms as mom because that was someone else who was a caregiver in my life and treated me like their own when I was around. Also they called her mom when they were around her. We weren’t the only kids I knew that did this so I thought it was normal.

What did you call your best friends parents growing up?