Is it supposed to change for existing installs? Mine did not change. Not complaining I prefer no accents. Fresh install on my laptop has it tho.
Plasma theming is... special. Enable menu / panel transparency and you'll change theme 800x for it to actually apply your setting, then it randomly drops it like it has again for me.
Typical, switch to light theme and back again and now I have the accent colours. 👍️
Got transparency back, but when you have a window maximised on that screen transparency goes away