I changed a settings for the default dark mode, then created a new test account and I can see the dark/light toggle in the burger menu. I guess this is fixed.
Can you check if you see the toggle in the burger menu?
here a preview of what you should see:
what do you want us to test?
I can see it now on this account, I thought the issue was that it only showed up once you manually changed it in the user preferences? do you want me to make a new account to check this?
damn, I missed this message, Markus, but I think this issue was already solved