As children, my parents would buy my two brothers whatever they requested regardless of how expensive it was, allowed them to go on trips with them & threw them over the top birthday parties while I didn’t receive any.
For example, my brothers got to go to Disney for their birthday(s) while I stayed with my grandparents. (Fortunately my aunt / grandma took me to Disney few months later) After being called out, they said they couldn’t afford the trip for 5
As we got a little older my parents had us working in their business after school & weekends...they gave both my brothers allowances for helping out while I didn’t receive anything (& was expected to do more)
I wish it was just financial abuse though, my parents always said very hurtful things, they’d make comments when I entered the room & I honestly still don’t know what I did wrong. When my brother graduated high school, they gave him an all inclusive trip around Europe for the summer. When I graduated the next year, I didn’t even get a party from them.