Ensure text remains visible during webfont load

Hi again Tom, hoe you are well.
Here trying to pick your brain a bit.

I’m trying to optimise the speed of my site by implementing, as Google says, the following: “Leverage the font-display CSS feature to ensure text is user-visible while webfonts are loading.”

I’m using Google fonts, but haven’t been successful at it.
I have around 7 warnings with different variations of this url
https://fonts.gstatic.com/s/poppins/v5/pxiByp8kv8JHgFVrLGT9Z1xlFd2JQEk.woff2

This is how I currently set the font in the custom css area in wordpress (I’m not CSS nor font savvy):

body,button,input,select,textarea{font-family:Poppins,Roboto,Arial,sans-serif;font-size:19px}

Any help you can provide is greatly appreciated!