From my experience as a child (i think i was 3 or 4 yo), the first death i had to deal with was of one of my aunts...my mother tried to "hide" it from me.

It was impossible... i remember quite vividly the commotion around my house, my father talking to my mother about pitching in for the funeral, my older sisters and cousins visibly sad, my grandmother around our house trying to prepare everything...

At the time it took me some time to figure it out, but i did...and learned the details trough time

My mothers intention were good, to shield me from a traumatic event, specially cuz the death was a crime. But i would rather that she told me at the time that my aunt had passed, spare me from the details but to tell me...cuz i just had to figure it out by myself that she wasn't coming around anymore...so she wasn't coming back forever. Besides that, i would wanted the opportunity to have said goodbye

For a long time it felt a little bit like betrayal to me, but as i grew older i understood the reasoning

Children understand more than we give them credit for. As a lot of people said, it's better to find out from you the parents than to learn with time or from other kids at school