ADVANCED EDITOR TOOLS WHITE FONT

Hmmm, if you’re using a white font, what is the background for it on the front-end? Generally if there is a background color on the front-end, and it is added by the theme, it should be in the editor too (assuming you’re using the classic (TinyMCE) editor).

If not, you can try adding a suitable background color to the editor iframe by using the Advanced TinyMCE Configuration plugin. Description of the setting is here: https://www.tiny.cloud/docs-4x/configure/content-appearance/#content_style.