Hello marius van Rijnsoever,
Thank you for reporting this issue. I apologize for the inconvenience you're experiencing with the blank Global Configuration page in Joomla 6.
To help me investigate this further, would you be willing to grant me temporary administrative access to your site? This will allow me to diagnose and resolve the problem directly.
Before providing credentials, I highly recommend creating a full backup of your site to ensure data security.
Looking forward to your response.
Best regards