Individual WS2812B circuit: Do i need a capacitor?: Power distribution?
If you have the WS2812B-2020 model then it says many times in the datasheet that the capacitor is not needed.
For any other earlier version of the WS2812B which is not the WS2812B-2020 model the capacitors are needed.
Capacitor is 100nF ceramic. Each chip must have a capacitor near it, one larger capacitor far away will not work.