Refused to load the font 'data:font/woff.....'it violates the following Content Security Policy directive: "default-src 'self'". Note that 'font-src'

For me it was because of the Chrome extension 'Grammarly'. After disabling that, I did not get the error.

To fix this specific error, CSP should include this:

font-src 'self' data:;

So, index.html meta should read:

<meta http-equiv="Content-Security-Policy" content="font-src 'self' data:; img-src 'self' data:; default-src 'self' http://121.0.0:3000/">

For what it's worth - I had a similar issue, assuming it's related to a Chrome update.

I had to add font-src, and then specify the url because I was using a CDN

<meta http-equiv="Content-Security-Policy" content="default-src 'self'; font-src 'self' data: fonts.gstatic.com;">