As per topic. Mainly applies to main bar, context menus and 'left bar' buttons.

I'm attaching screenshot comparing QtC 4.10 to 4.11 Take a look, for example, at the inactive 'Build' menu item in the top bar - I'm not sure if I could read it without knowing what it said earlier : P

I'm using Kubuntu that reports itself as:

Distributor ID: Ubuntu
Description:    Ubuntu 18.04.3 LTS
Release:        18.04
Codename:       bionic

With Plasma version:

KDE Plasma Version: 5.12.9
KDE Frameworks Version: 5.44.0
Qt Version: 5.9.5