Hello Jan,
Good day!! Thank you for posting in Microsoft Community. We are happy to help you.
- May I know if this issue only occurs in a specific SharePoint site? Could you please provide a screenshot of your SharePoint page?
- To my knowledge, generally, we can use a theme to change the colors of a SharePoint site, from Settings > Change the look > Theme. Depends on the theme's color, font color may be black or white.
So I'd like to know which theme are you using now? Or did you make any customization on the site?
- By the way, do other users who have permission to access the SharePoint site have the same issue?
Look forward to your reply. Thanks for your time and cooperation!
Please understand that our initial reply may not always immediately resolve the issue. However, with your help and more detailed information, we can work together to find a solution.
Sincerely,
Tina | Microsoft Community Moderator