You can turn on night mode in facebook messenger

[I_didnt_do_it]

Go to a conversation and send a crescent moon emoji, you'll then see a moon falling animation and a notification that you have found night mode, with "turn on in settings" , tap on that and turn it on and there ya go. And it's true dark too. Very useful especially for those with amoled and superamoled displays.

 

[Jason Ahr]

worked for me on lg