Some (seemingly not QT) packages have issues with the default Plasma theme (which I assume was Solus Dark) since I rebooted after yesterday's update. The dark theme in Lutris for example is no longer respected:
The button colours change colour too.
Similarly in Firefox when downloading the button background changes from white to black to blue:
In the second case "Open with..." is selected but hard to see.
I tried to change the theme to Breeze or Breeze Dark but the issues persist. Also when I selected Solus Dark that was not the same theme as originally (which was whatever defaulted with the iso), not sure if it was changed or if it's just been changed due to this.
I am not certain if I rebooted after last weeks update so can't be 100% sure it was from yesterday's. Apologies for vagueness.