Allowed hosts didn't work so I added it to the astro.config.mjs.

astro.config.mjs

@@ -8,4 +8,13 @@ import { defineConfig } from 'astro/config';
 export default defineConfig({
 	site: 'https://example.com',
 	integrations: [mdx(), sitemap()],
+	vite: {
+    	server: {
+      	allowedHosts: [
+        	"seans.cloud",
+        	"www.seans.cloud",
+        	".seans.cloud", // allows all subdomains too
+      		],
+    	},
+  	},
 });