Sending, receiving, and organizing email in Outlook on the web for business
Also having this same issue. Looks like MS has yet to do anything about it based off all the replies for this. This is incredibly annoying seeing as my eyes take enough light beating as is. My eyes are very sensitive, and the dark mode helps to relieve my eyes of some of the light I have to look at during my workday.
Microsoft, please actually do something about this for those of us who need dark mode due to sensory issues/just wanting to be able to implement dark mode in general. Can't say I'm surprised by the lack of communication/effort from MS though.