add metadata base url

src/app/layout.js

···
 
 export const metadata = {
   title: process.env.SITENAME,
-  description: process.env.DESCRIPTION
+  description: process.env.DESCRIPTION,
+  metadataBase: new URL('https://'+process.env.DOMAIN),
 };
 
 export const viewport = "width=device-width, initial-scale=1.0"