Your ROOT_URL in app.ini is https://source.parasitstudio.de:63000/ but you are visiting https://source.parasitstudio.de/wirtz/MicroDexed/src/commit/0e9f481041fb07556f046b84aa7c4141fa693498/third-party/ArduinoJson/examples/JsonServer
You should set ROOT_URL correctly, otherwise the web may not work correctly.