For those wondering about the significance of the X and Y capacitors, they are specifically designed for use in safety critical positions. X capacitors can withstand high voltage pulses without failing, and Y type are designed to fail open circuit, since they are connected between live and earth, where a short circuit could lead to electrocution. The numbers work the reverse of what you might expect - lower numbers give more protection. It is not enough to use capacitors with a high enough voltage rating in these positions. They need the safety rating as well.
See:?https://www.allaboutcircuits.com/technical-articles/safety-capacitor-class-x-and-class-y-capacitors/
