Black Swan
A 'black swan' is an unpredictable, unforeseen or random event with potentially severe and negative consequences e.g. 9/11; 2008's financial recession; COVID '19.
Why it matters
Moving away from terms which infer positive or negative connotations associated to colour and colour binary (e.g. Black = Bad and White = Good) to distance from cultural views of good & evil, especially related to skin colour or appearance. Specifically, this associates 'black' with a negative phenomenon or event, typically impacting lives.
Instead try saying:
Unpredictable, devastating event
Further External Reading Link