It's a strange one for me.
My mum died very suddenly and unexpectedly (she collapsed at home and was never revived) so we didn't know what she had died of.
When I told people, I merely said "my mum has just died very suddenly" (or something along those lines). She wasn't elderly [65] or ill but people seemed to know it wasn't anything untoward?
People did ask - the main response was "what happened?". In fact I think everyone I messaged or contacted asked this question. I wasn't offended at all.
However I don't use social media so there was no announcement of death and I can only go by my own experience. We didn't know why mum died (heart failure / recorded as natural in the end) but I assume if it had been an illness most people I told of her death would have known she was ill? And if it had been an accident I'd have said that?
I do think its human nature to want that knowledge / closure but depends on lots of things.
My best friend messaging me and saying "oh my fucking God, what happened, are you all ok?" Is very different to the neighbour who stopped me before the undertakers had even taken mum's body and asked me what had happened..... she got told very impolitely that I was busy dealing with the undertakers so I didn't have time to talk.
I know I'd have had zero tolerance for someone I went to school with two decades ago asking "oh no hun, what happened to your mum?".