Facebook Dark Mode missing?

I can't access dark mode in Facebook on my Fold 3. Weird I was able to access it on my Note 10+. Don't want to enable it via developer options, since with it other apps goes dark and I want it to be white. Any tip?

You can change the ratio like I suggested above or you can fix this permanently by disabling multi window for all apps in the labs section in settings... that's the only way I know of.
 
You can change the ratio like I suggested above or you can fix this permanently by disabling multi window for all apps in the labs section in settings... that's the only way I know of.
It worked! Thank you very much!

But, no more fullscreen...