Windows 10 Photos App background turns from black to grey

[eragontrible]

I don't know how but when i was going through some pictures i noticed that the background has changed from black to gray. It's very annoying having the background not being a transparent black but blocks the entirety with the nasty<ModEdit>grey color. Does anyone know how to revert it?
https://imgur.com/a/CyTzqEl

Edit: please watch the language

 

[Colif]

That appears to be the default color for the application and has been an ongoing complaint since 2015, transparency being one of the reasons. There are a few suggested fixes here - https://answers.microsoft.com/en-us/windows/forum/apps_windows_10-photos/change-the-background-colour-of-windows-10-photo/3a2e0364-cf5e-4909-83ce-a2501bb8b512