yarn build

pages/_document.js

@@ -13,7 +13,7 @@ class MyDocument extends Document {
             content="width=device-width, initial-scale=1, shrink-to-fit=no"
           />
           <meta name="theme-color" content="#000000" />
-          <link rel="shortcut icon" href={require("assets/img/favicons.png")} />
+          <link rel="shortcut icon" href={require("assets/img/favicon.png")} />
           <link
             rel="apple-touch-icon"
             sizes="76x76"