I've seen this capacitor: https://api.kemet.com/component-edge/download/datasheet/C0603C221JDGACAUTO.pdf
It is a 0603 capacitor with a 1000VDC rating. As I am familiar with IPC2221, this did not sound right.
As can be seen here: Minimum clearance between two traces that have a potential difference of 1000VDC The separation of two 1000V uncoated conductors should be at least 200mils. 0603 capacitors have only 20 mils separation! How can this be?