Ensure that you are using the Kestrel server without the IIS Integration. Place app.UseCompressedStaticFiles(); before app.UseStaticFiles(); in Startup.Configure().

This will ensure that you application will serve pre compressed gzipped(filename.ext.gz) and brotli(filename.ext.br) compressed files if the browser supports it.

Checkout the example for setup.

This solution is based on @neyromant from the following issue dotnet/aspnetcore#1584 (comment).