I had the similar issue (on Windows 11 Dark mode). ParaView 6.0 inherits that from the system settings. I tried to use it in Dark mode, but I for one found it, unfortunately, unusable. I uninstalled it immediately and installed 5.13.2.
I am not a big fan of workarounds for a basic setting like that. I hope this gets fixed in the next release so users can choose between the light and dark mode.