I had forgotten to use the asset prefix in next.config.mjs

Author: DaltheCow

.github/workflows/ui-development.yml

@@ -104,7 +104,6 @@ jobs:
           export GIT_SHA=${GIT_SHA}
           export USE_MOCK_DATA=${USE_MOCK_DATA}
           npm run build
-          cat out/index.html
         working-directory: ui
 
       - name: Deploy to GitHub Pages

ui/next.config.mjs

@@ -1,6 +1,7 @@
 /** @type {import('next').NextConfig} */
 const nextConfig = {
   output: 'export',
+  assetPrefix: process.env.ASSET_PREFIX || '',
   webpack(config) {
     // Grab the existing rule that handles SVG imports
     const fileLoaderRule = config.module.rules.find((rule) => rule.test?.test?.('.svg'));