Staudey The other possible solution using dconf-editor is described here: https://discuss.getsol.us/d/8463-fix-for-dark-themes-with-blaring-white-applications
DISCLAIMER: I haven't been active on this forum for some time or read all of the responses in this post.
Since one of my posts was mentioned as a solution for theming issues I wanted to point out that I just wrote another reply in the same post explaining how to install flatpak apps that follow theming directives properly so users have the option of using Dolphin temporarily while fixes to existing are worked on.
This solution will work for Dolphin AND ANY OTHER FLATPAK APP INSTALLED so it can offer a solution for using Dolphin temporarily in lieu or Nautilus OR any Gnome/Budgie/GTK app available on flatpak that might be giving people issues when installed from the repo.
Thank you to everyone who have taken on the herculean task of fixing a widespread issue like this and I very much hope this can be a potential solution for some of the problems people are facing.