I marked it as the solution because I reinstalled Power BI and my UI returned back to dark instead of light.
It didn't the first time I tried it so I went to "Add or Remove Programs" and uninstalled "Power BI". I saw I had two Power BI apps for some reason, so I uninstalled both of them. Reinstalled Power BI and checked to see if there was only 1 app installed, there is. Open Power BI Desktop, the UI was dark.
That's very interesting. If this is true on my PC as well, they must have released a patch to revert to dark mode. I can't see how it can happen any other way (except by re-installing the May version). @v-lili6-msft , can you perhaps shed some light on this (which does not mean "make our Desktop UI light" 😉 )
I'll give it a try (i.e. uninstalling and re-installing the very same version) in the next few days and let you know if my dark mode has also returned.
Just want to call out that even though I marked this issue as solved, which it was at the time. Today, I got a notice to update Power BI when I launced it on my desktop. So I went ahead and clicked on the notice and it took me to a page to download. Once installation was completed, I launce Power BI Desktop and guess what...... It's back to white theme again!
Does anyone actually like this theme? It burns my eyes.