Several issues:
- Text on "Find in Files" and "Replace in Files" is black on dark background
- Text in boxes is mostly light gray on white
- On hover/focus, the text in the search box becomes unreadable. In this screenshot there's "abcdef" with "def" selected and "abc" completely unreadable. The selected text is not that readable in itself.

I can take a swing at a fix if you could let me know what elements should I be looking for in the theme editor.
Microsoft Visual Studio Community 2019
Version 16.11.0
VisualStudio.16.Release/16.11.0+31605.320
Microsoft .NET Framework
Version 4.8.04084
Color Themes for Visual Studio 1.0.11