Uncompressed text content resources - UPDATE JSON TO SAY RESOURCE URLS IN DESCRIPTION
This means that the URL in question contains text content that has not been compressed.
Why is this important?
Text compression minimizes the byte size of network responses that include text content. Compressing text content with gzip saves download bytes and reduces bandwidth for the user - less bytes downloaded means faster page loads.
What does the Hint check?
This Hint will trigger for any internal HTML URL, or internal resource URL, which contains text content that has not been compressed.
How do you resolve this issue?
You need to enable text compression on the server(s) that served these responses in order to resolve this issue.
Configure your server to compress the response with Brotli, if the browser supports it. Brotli is a newer compression format, but it's not universally supported in browsers. Do a search for "how to enable Brotli compression in <server>" to learn how to implement it, where <server> is the name of your server.
Use GZIP as a fallback to Brotli. GZIP is universally supported in all modern browsers, but is less efficient than Brotli.