Your ROOT_URL in app.ini is https://source.parasitstudio.de:63000/ but you are visiting https://source.parasitstudio.de/wirtz/MiniDexed/commit/8408ab86d640a0678ac36de1df2017e0f7627835?style=unified&whitespace=ignore-change
You should set ROOT_URL correctly, otherwise the web may not work correctly.
* Raspberry Pi 1, 2, 3, 4, or 400 (Zero and Zero 2 can be used but need HDMI or a supported i2s DAC for audio out). On Raspberry Pi 1 and on Raspberry Pi Zero there will be severely limited functionality (only one tone generator instead of 8)