Cause of death?
Haven't seen it reported. Though the police say she was found 'unresponsive' and the death isn't being treated as suspicious.
https://www.theguardian.com/music/2023/jul/27/sinead-oconnor-was-found-unresponsive-in-london-flat-says-met
Suicide or accidental overdose I take it?
Given the fact the samaritans number is linked on the article, I'm guessing suicide.