Setting service worker to exclude certain urls only

So, considering, you have not posted any code relevant to the service worker, you might consider adding a simple if conditional inside the code block for fetch

This code block should already be there inside your service worker.Just add the conditionals

self.addEventListener( 'fetch', function ( event ) {

    if ( event.request.url.match( '^.*(\/blog\/).*$' ) ) {
        return false;
    }
     // OR

    if ( event.request.url.indexOf( '/blog/' ) !== -1 ) {
        return false;
    }
    //    **** rest of your service worker code ****

note you can either use the regex or the prototype method indexOf.
per your whim.

the above would direct your service worker, to just do nothing when the url matches /blog/